Patrick Krantz; Alex Tyner; Pallab Goswami; Venkat Chandrasekhar
Colossal Spontaneous Hall Effect and Emergent Magnetism in KTaO3 Two-Dimensional Electron Gases Journal Article
In: 2022.
Abstract | Links | BibTeX | Tags: AMR, magnetic impurity, Magnetism, perovskite, Superconductivity
@article{nokey,
title = {Colossal Spontaneous Hall Effect and Emergent Magnetism in KTaO3 Two-Dimensional Electron Gases},
author = {Patrick Krantz and Alex Tyner and Pallab Goswami and Venkat Chandrasekhar},
url = {https://arxiv.org/abs/2209.10534},
year = {2022},
date = {2022-09-21},
urldate = {2022-09-21},
abstract = {There has been intense recent interest in the two-dimensional electron gases (2DEGs) that form at the surfaces and interfaces of KTaO$_3$ (KTO), with the discovery of superconductivity at temperatures significantly higher than those of similar 2DEGs based on SrTiO$_3$ (STO). Here we demonstrate that KTO 2DEGs fabricated under conditions that suppress the superconductivity show a large spontaneous Hall effect at low temperatures. The transverse response is asymmetric in an applied perpendicular magnetic field and becomes hysteretic at millikelvin temperatures. The hysteresis is due to long range magnetic order arising from local Ta$^{4+}$ moments. However, the most striking features of the data are the asymmetry of the transverse response and the large spontaneous transverse resistance at zero field, which can be a significant fraction of the longitudinal resistance and depends on crystal orientation. Both effects are due to the presence of a dominant contribution to the transverse response that is symmetric in perpendicular field, suggesting that its origin is topological in nature. We argue that this contribution arises from Berry curvature dipoles coupled with nonequilibrium conditions induced by the measuring current.},
keywords = {AMR, magnetic impurity, Magnetism, perovskite, Superconductivity},
pubstate = {published},
tppubtype = {article}
}
There has been intense recent interest in the two-dimensional electron gases (2DEGs) that form at the surfaces and interfaces of KTaO$_3$ (KTO), with the discovery of superconductivity at temperatures significantly higher than those of similar 2DEGs based on SrTiO$_3$ (STO). Here we demonstrate that KTO 2DEGs fabricated under conditions that suppress the superconductivity show a large spontaneous Hall effect at low temperatures. The transverse response is asymmetric in an applied perpendicular magnetic field and becomes hysteretic at millikelvin temperatures. The hysteresis is due to long range magnetic order arising from local Ta$^{4+}$ moments. However, the most striking features of the data are the asymmetry of the transverse response and the large spontaneous transverse resistance at zero field, which can be a significant fraction of the longitudinal resistance and depends on crystal orientation. Both effects are due to the presence of a dominant contribution to the transverse response that is symmetric in perpendicular field, suggesting that its origin is topological in nature. We argue that this contribution arises from Berry curvature dipoles coupled with nonequilibrium conditions induced by the measuring current.
Venkat Chandrasekhar
Probing the topological band structure of diffusive multiterminal Josephson junction devices with conductance measurements Journal Article
In: Applied Physics Letters, vol. 121, pp. 222601, 2022.
Abstract | Links | BibTeX | Tags: Andreev reflection, Mesoscopic quantum transport, phase coherence, Proximity effect, Superconductivity
@article{nokey,
title = {Probing the topological band structure of diffusive multiterminal Josephson junction devices with conductance measurements},
author = {Venkat Chandrasekhar},
url = {https://arxiv.org/abs/2209.04743
https://aip.scitation.org/doi/full/10.1063/5.0125708},
year = {2022},
date = {2022-09-10},
urldate = {2022-09-10},
journal = {Applied Physics Letters},
volume = {121},
pages = {222601},
abstract = {The energy of an Andreev bound state in a clean normal metal in contact with two superconductors disperses with the difference Δϕ in the superconducting phase between the superconductors in much the same way as the energies of electrons in a one-dimensional crystal disperse with the crystal momentum k of the electrons. A normal metal with n superconductors maps on to a n−1 dimensional crystal, each dimension corresponding to the phase difference ϕi between a specific pair of superconductors. The resulting band structure as a function of the phase differences {Δϕi} has been proposed to have a topological nature, with gapped regions characterized by different Chern numbers separated by regions where the gap in the quasiparticle spectrum closes. A similar complex evolution of the quasiparticle spectrum with {Δϕi} has also been predicted for diffusive normal metals in contact with multiple superconductors. Here we show that the variation of the density of states at the Fermi energy of such a system can be directly probed by relatively simple conductance measurements, allowing rapid characterization of the energy spectrum.},
keywords = {Andreev reflection, Mesoscopic quantum transport, phase coherence, Proximity effect, Superconductivity},
pubstate = {published},
tppubtype = {article}
}
The energy of an Andreev bound state in a clean normal metal in contact with two superconductors disperses with the difference Δϕ in the superconducting phase between the superconductors in much the same way as the energies of electrons in a one-dimensional crystal disperse with the crystal momentum k of the electrons. A normal metal with n superconductors maps on to a n−1 dimensional crystal, each dimension corresponding to the phase difference ϕi between a specific pair of superconductors. The resulting band structure as a function of the phase differences {Δϕi} has been proposed to have a topological nature, with gapped regions characterized by different Chern numbers separated by regions where the gap in the quasiparticle spectrum closes. A similar complex evolution of the quasiparticle spectrum with {Δϕi} has also been predicted for diffusive normal metals in contact with multiple superconductors. Here we show that the variation of the density of states at the Fermi energy of such a system can be directly probed by relatively simple conductance measurements, allowing rapid characterization of the energy spectrum.
Kevin M. Ryan; Carlos G. Torres-Castanedo; Dominic P. Goronzy; David A. Garcia Wetter; Matthew J Reagor; Mark Field; Cameron J Kopas; Jayss Marshall; Michael J. Bedzyk; Mark C. Hersam; Venkat Chandrasekhar
Characterization of Nb films for superconducting qubits using phase boundary measurements Journal Article
In: Applied Physics Letters, vol. 121, pp. 202601, 2022.
Abstract | Links | BibTeX | Tags: epitaxial, instrumentation, Superconductivity, superconductor
@article{Ryan2022,
title = {Characterization of Nb films for superconducting qubits using phase boundary measurements},
author = {Kevin M. Ryan and Carlos G. Torres-Castanedo and Dominic P. Goronzy and David A. Garcia Wetter and Matthew J Reagor and Mark Field and Cameron J Kopas and Jayss Marshall and Michael J. Bedzyk and Mark C. Hersam and Venkat Chandrasekhar},
url = {https://arxiv.org/abs/2207.13125
https://aip.scitation.org/doi/10.1063/5.0119932},
year = {2022},
date = {2022-07-26},
urldate = {2022-07-26},
journal = {Applied Physics Letters},
volume = {121},
pages = {202601},
abstract = {Continued advances in superconducting qubit performance require more detailed understandings of the many sources of decoherence. Within these devices, two-level systems arise due to defects, interfaces, and grain boundaries, and are thought to be a major source of qubit decoherence at millikelvin temperatures. In addition to Al, Nb is a commonly used metalization layer for superconducting qubits. Consequently, a significant effort is required to develop and qualify processes that mitigate defects in Nb films. As the fabrication of complete superconducting qubits and their characterization at millikelvin temperatures is a time and resource intensive process, it is desirable to have measurement tools that can rapidly characterize the properties of films and evaluate different treatments. Here we show that measurements of the variation of the superconducting critical temperature Tc with an applied external magnetic field H (of the phase boundary Tc−H) performed with very high resolution show features that are directly correlated with the structure of the Nb films. In combination with x-ray diffraction measurements, we show that one can even distinguish variations quality and crystal orientation of the grains in a Nb film by small but reproducible changes in the measured superconducting phase boundary.},
keywords = {epitaxial, instrumentation, Superconductivity, superconductor},
pubstate = {published},
tppubtype = {article}
}
Continued advances in superconducting qubit performance require more detailed understandings of the many sources of decoherence. Within these devices, two-level systems arise due to defects, interfaces, and grain boundaries, and are thought to be a major source of qubit decoherence at millikelvin temperatures. In addition to Al, Nb is a commonly used metalization layer for superconducting qubits. Consequently, a significant effort is required to develop and qualify processes that mitigate defects in Nb films. As the fabrication of complete superconducting qubits and their characterization at millikelvin temperatures is a time and resource intensive process, it is desirable to have measurement tools that can rapidly characterize the properties of films and evaluate different treatments. Here we show that measurements of the variation of the superconducting critical temperature Tc with an applied external magnetic field H (of the phase boundary Tc−H) performed with very high resolution show features that are directly correlated with the structure of the Nb films. In combination with x-ray diffraction measurements, we show that one can even distinguish variations quality and crystal orientation of the grains in a Nb film by small but reproducible changes in the measured superconducting phase boundary.
Taewan Noh; Andrew Kindseth; Venkat Chandrasekhar
The Nonlocal Superconducting Quantum Interference Device Journal Article
In: Physical Review B, vol. 104, pp. 064503, 2021.
Abstract | Links | BibTeX | Tags: Andreev reflection, Mesoscopic quantum transport, Proximity effect, Superconductivity
@article{Noh2020,
title = {The Nonlocal Superconducting Quantum Interference Device},
author = {Taewan Noh and Andrew Kindseth and Venkat Chandrasekhar},
url = {https://journals.aps.org/prb/abstract/10.1103/PhysRevB.104.064503},
doi = {10.1103/PhysRevB.104.064503},
year = {2021},
date = {2021-08-04},
urldate = {2020-11-12},
journal = {Physical Review B},
volume = {104},
pages = {064503},
abstract = {Superconducting quantum interference devices (SQUIDs) that incorporate two superconductor/insulator/superconductor (SIS) Josephson junctions in a closed loop form the core of some of the most sensitive detectors of magnetic and electric fields currently available. SQUIDs in these applications are typically operated with a finite voltage which generates microwave radiation through the ac Josephson effect. This radiation may impact the system being measured. We describe here a SQUID in which the Josephson junctions are formed from strips of normal metal (N) in good electrical contact with the superconductor (S). Such SNS SQUIDs can be operated under a finite voltage bias with performance comparable or potentially better than conventional SIS SQUIDs. However, they also permit a mode of operation that is based on the unusual interplay of quasiparticle currents and supercurrents in the normal metal of the Josephson junction. The method allows measurements of the flux dependence of the critical current of the SNS SQUID without applying a finite voltage bias across the SNS junction, enabling sensitive flux detection without generating microwave radiation.},
keywords = {Andreev reflection, Mesoscopic quantum transport, Proximity effect, Superconductivity},
pubstate = {published},
tppubtype = {article}
}
Superconducting quantum interference devices (SQUIDs) that incorporate two superconductor/insulator/superconductor (SIS) Josephson junctions in a closed loop form the core of some of the most sensitive detectors of magnetic and electric fields currently available. SQUIDs in these applications are typically operated with a finite voltage which generates microwave radiation through the ac Josephson effect. This radiation may impact the system being measured. We describe here a SQUID in which the Josephson junctions are formed from strips of normal metal (N) in good electrical contact with the superconductor (S). Such SNS SQUIDs can be operated under a finite voltage bias with performance comparable or potentially better than conventional SIS SQUIDs. However, they also permit a mode of operation that is based on the unusual interplay of quasiparticle currents and supercurrents in the normal metal of the Josephson junction. The method allows measurements of the flux dependence of the critical current of the SNS SQUID without applying a finite voltage bias across the SNS junction, enabling sensitive flux detection without generating microwave radiation.
Taewan Noh
Nonlocal correlations in a proximity-coupled normal metal PhD Thesis
Northwestern University, 2019.
Abstract | BibTeX | Tags: Andreev reflection, Magnetism, Proximity effect, Superconductivity
@phdthesis{Noh2019,
title = {Nonlocal correlations in a proximity-coupled normal metal},
author = {Taewan Noh},
year = {2019},
date = {2019-12-01},
address = {2145 Sheridan Road, Evanston, IL 60208},
school = {Northwestern University},
abstract = {A superconductor-normal metal-superconductor (SNS) junction is capable of carrying supercurrent due to the Josephson coupling between the two superconductors. More inter- estingly, this coupling is maintained through the normal metal in a length determined by the Thouless energy of the normal metal, which can be a few microns, much longer than the case of conventional Josephson junction consisting of two superconductors separated by a thin insulator, where the thickness is only a few nanometers. This provides us with a capability of measuring the electric potential in the proximity-coupled normal metal by placing multiple probes on it. In particular, in this thesis we present the experimental results of our attempt to search nonlocal correlations mediated by a proximity-coupled normal metal via electrical transport measurements. At very low temperatures, with an overall dependence on the bias current seemingly analogous to that observed in prior experiments on NSN structures, the nonlocal differential resistance exhibits a peculiar dip in a small range of bias current. In addition to the qualitative explanation that accounts for the nonlocal differential resistance arising from the separation of quasiparticle current due to the Josephson coupling between the two superconductors, further analysis based on the quasiclassical theory of superconduc- tivity reveals that the central dip can be attributed to penetration of pair correlations into the proximity-coupled normal metal from both superconductors in a coherent manner. While the processes analogous to crossed Andreev reflection and elastic cotunneling observed in a superconductor are yet to be found, our data and analysis provide insights on the physics behind the interplay between the quasiparticle current and the supercurrent which gives rise to the observed nonlocal correlations in a proximity-coupled normal metal.
Beside the nonlocal correlations in a proximity-coupled normal metal, we also investigated electrical transport through a heterostructure including double superconductor-ferromagnet (FS) interfaces. In addition to a typical signature of spin imbalance due to the Zeeman splitting in the density of states (DOS) of the quasiparticles in a superconductor, an inter- esting feature in a small range of bias current has been observed, which might be related to spin-dependent phenomena at FS interfaces although further investigation in a simpler geometry of the sample is required to elucidate the exact mechanism.},
keywords = {Andreev reflection, Magnetism, Proximity effect, Superconductivity},
pubstate = {published},
tppubtype = {phdthesis}
}
A superconductor-normal metal-superconductor (SNS) junction is capable of carrying supercurrent due to the Josephson coupling between the two superconductors. More inter- estingly, this coupling is maintained through the normal metal in a length determined by the Thouless energy of the normal metal, which can be a few microns, much longer than the case of conventional Josephson junction consisting of two superconductors separated by a thin insulator, where the thickness is only a few nanometers. This provides us with a capability of measuring the electric potential in the proximity-coupled normal metal by placing multiple probes on it. In particular, in this thesis we present the experimental results of our attempt to search nonlocal correlations mediated by a proximity-coupled normal metal via electrical transport measurements. At very low temperatures, with an overall dependence on the bias current seemingly analogous to that observed in prior experiments on NSN structures, the nonlocal differential resistance exhibits a peculiar dip in a small range of bias current. In addition to the qualitative explanation that accounts for the nonlocal differential resistance arising from the separation of quasiparticle current due to the Josephson coupling between the two superconductors, further analysis based on the quasiclassical theory of superconduc- tivity reveals that the central dip can be attributed to penetration of pair correlations into the proximity-coupled normal metal from both superconductors in a coherent manner. While the processes analogous to crossed Andreev reflection and elastic cotunneling observed in a superconductor are yet to be found, our data and analysis provide insights on the physics behind the interplay between the quasiparticle current and the supercurrent which gives rise to the observed nonlocal correlations in a proximity-coupled normal metal.
Beside the nonlocal correlations in a proximity-coupled normal metal, we also investigated electrical transport through a heterostructure including double superconductor-ferromagnet (FS) interfaces. In addition to a typical signature of spin imbalance due to the Zeeman splitting in the density of states (DOS) of the quasiparticles in a superconductor, an inter- esting feature in a small range of bias current has been observed, which might be related to spin-dependent phenomena at FS interfaces although further investigation in a simpler geometry of the sample is required to elucidate the exact mechanism.
Beside the nonlocal correlations in a proximity-coupled normal metal, we also investigated electrical transport through a heterostructure including double superconductor-ferromagnet (FS) interfaces. In addition to a typical signature of spin imbalance due to the Zeeman splitting in the density of states (DOS) of the quasiparticles in a superconductor, an inter- esting feature in a small range of bias current has been observed, which might be related to spin-dependent phenomena at FS interfaces although further investigation in a simpler geometry of the sample is required to elucidate the exact mechanism.
V. V. Bal; Z. Huang; K. Han; Ariando; T. Venkatesan; V. Chandrasekhar
Low temperature magnetoresistance of (111) (La0.3Sr0.7)(Al0.65Ta0.35)/SrTiO3 Journal Article
In: Physical Review B, vol. 99, pp. 035408, 2019.
Abstract | Links | BibTeX | Tags: epitaxial, magnetic impurity, Magnetism, perovskite, phase coherence, spin glass, Superconductivity
@article{Bal2018,
title = {Low temperature magnetoresistance of (111) (La0.3Sr0.7)(Al0.65Ta0.35)/SrTiO3},
author = {V. V. Bal and Z. Huang and K. Han and Ariando and T. Venkatesan and V. Chandrasekhar},
url = {https://journals.aps.org/prb/abstract/10.1103/PhysRevB.99.035408},
doi = {https://doi.org/10.1103/PhysRevB.99.035408},
year = {2019},
date = {2019-01-03},
journal = {Physical Review B},
volume = {99},
pages = {035408},
abstract = {The two-dimensional conducting interfaces in SrTiO3-based systems are known to show a variety of coexisting and competing phenomena in a complex phase space. Magnetoresistance measurements, which are typically used to extract information about the various interactions in these systems, must be interpreted with care, since multiple interactions can contribute to the resistivity in a given range of magnetic field and temperature. Here we review all the phenomena that can contribute to transport in SrTiO3-based conducting interfaces at low temperatures. We apply this understanding to the perpendicular magnetoresistance data of the high-mobility system of (111) oriented (La0.3Sr0.7)(Al0.65Ta0.35)O3/STO heterostructures, and find an excess negative magnetoresistance contribution which cannot be explained by weak localization alone. We argue that contributions from magnetic scattering as well as electron-electron interactions, combined with weak localization/antilocalization, can provide a possible explanation for the observed magnetoresistance.},
keywords = {epitaxial, magnetic impurity, Magnetism, perovskite, phase coherence, spin glass, Superconductivity},
pubstate = {published},
tppubtype = {article}
}
The two-dimensional conducting interfaces in SrTiO3-based systems are known to show a variety of coexisting and competing phenomena in a complex phase space. Magnetoresistance measurements, which are typically used to extract information about the various interactions in these systems, must be interpreted with care, since multiple interactions can contribute to the resistivity in a given range of magnetic field and temperature. Here we review all the phenomena that can contribute to transport in SrTiO3-based conducting interfaces at low temperatures. We apply this understanding to the perpendicular magnetoresistance data of the high-mobility system of (111) oriented (La0.3Sr0.7)(Al0.65Ta0.35)O3/STO heterostructures, and find an excess negative magnetoresistance contribution which cannot be explained by weak localization alone. We argue that contributions from magnetic scattering as well as electron-electron interactions, combined with weak localization/antilocalization, can provide a possible explanation for the observed magnetoresistance.
Varada Vilas Bal
Transport Measurements on (111) Oriented (La0.3Sr0.7)(Al0.65Ta0.35)O3/SrTiO3 Heterostructures PhD Thesis
Northwestern University, 2018.
Abstract | Links | BibTeX | Tags: epitaxial, Kondo effect, magnetic impurity, Magnetism, perovskite, spin-orbit scattering, Superconductivity, superconductor
@phdthesis{Bal2018b,
title = {Transport Measurements on (111) Oriented (La0.3Sr0.7)(Al0.65Ta0.35)O3/SrTiO3 Heterostructures},
author = {Varada Vilas Bal},
url = {http://www.nano.northwestern.edu/wp-content/uploads/2018/09/BalVarada_PhD_Thesis.pdf},
year = {2018},
date = {2018-09-01},
address = {Department of Physics},
school = {Northwestern University},
abstract = {At the interface of two dissimilar entities, something novel can emerge. This idea has driven a vast amount of fruitful work on semiconductor interfaces, and given us the digi- tal revolution. In the past decade, remarkable progress has been made in the synthesis and understanding of interfaces between oxides, opening up new avenues to explore fundamen- tal emergent physics at the interface, as well as to provide viable candidates to augment or even surpass the performance of conventional semiconductor electronics. The two- dimensional conducting interface in the (001) LaAlO3/SrTiO3 system is the most studied example of oxide interfaces, showing a wide range of coexisting and competing phenomena such as superconductivity, superconductor-insulator transitions, magnetism, and spin- orbit interactions. The (111) oriented LaAlO3/SrTiO3 system has been recently found to have a few surprises of its own, with intriguing anisotropies in many transport properties along different in-plane crystal directions. This thesis presents the first results on a different SrTiO3 based system: the conducting interface between (La0.3Sr0.7)(Al0.65Ta0.35) and (111) oriented SrTiO3, which has a smaller strain as compared to the LaAlO3/SrTiO3 system. Electrical transport measurements at cryogenic temperatures reveal that no systematic anisotropy is seen in transport properties, unlike in the case of (111) oriented LaAlO3/SrTiO3. High-field magnetotransport shows the presence of high-mobility carri- ers at high electron densities, and exhibits multiband behavior, tunable in situ using an electrical back-gate, similar to the LaAlO3/SrTiO3 system. The data allow us to draw specific conclusions about band ordering in the system, and point to possible differences between the band ordering in (111) (La0.3Sr0.7)(Al0.65Ta0.35)O3/SrTiO3 and (001) as well as (111) oriented LaAlO3/SrTiO3. Low-field magnetotransport reveals that a strong spin- orbit interaction emerges in the regime of low electron density, when the high-mobility carriers are depleted from the system, a trend which is opposite to that observed in (001) oriented LaAlO3/SrTiO3. The most striking feature is that at millikelvin temperatures, in the regime of low electron densities, concomitant with the development of strong spin- orbit interaction, magnetic order emerges.},
keywords = {epitaxial, Kondo effect, magnetic impurity, Magnetism, perovskite, spin-orbit scattering, Superconductivity, superconductor},
pubstate = {published},
tppubtype = {phdthesis}
}
At the interface of two dissimilar entities, something novel can emerge. This idea has driven a vast amount of fruitful work on semiconductor interfaces, and given us the digi- tal revolution. In the past decade, remarkable progress has been made in the synthesis and understanding of interfaces between oxides, opening up new avenues to explore fundamen- tal emergent physics at the interface, as well as to provide viable candidates to augment or even surpass the performance of conventional semiconductor electronics. The two- dimensional conducting interface in the (001) LaAlO3/SrTiO3 system is the most studied example of oxide interfaces, showing a wide range of coexisting and competing phenomena such as superconductivity, superconductor-insulator transitions, magnetism, and spin- orbit interactions. The (111) oriented LaAlO3/SrTiO3 system has been recently found to have a few surprises of its own, with intriguing anisotropies in many transport properties along different in-plane crystal directions. This thesis presents the first results on a different SrTiO3 based system: the conducting interface between (La0.3Sr0.7)(Al0.65Ta0.35) and (111) oriented SrTiO3, which has a smaller strain as compared to the LaAlO3/SrTiO3 system. Electrical transport measurements at cryogenic temperatures reveal that no systematic anisotropy is seen in transport properties, unlike in the case of (111) oriented LaAlO3/SrTiO3. High-field magnetotransport shows the presence of high-mobility carri- ers at high electron densities, and exhibits multiband behavior, tunable in situ using an electrical back-gate, similar to the LaAlO3/SrTiO3 system. The data allow us to draw specific conclusions about band ordering in the system, and point to possible differences between the band ordering in (111) (La0.3Sr0.7)(Al0.65Ta0.35)O3/SrTiO3 and (001) as well as (111) oriented LaAlO3/SrTiO3. Low-field magnetotransport reveals that a strong spin- orbit interaction emerges in the regime of low electron density, when the high-mobility carriers are depleted from the system, a trend which is opposite to that observed in (001) oriented LaAlO3/SrTiO3. The most striking feature is that at millikelvin temperatures, in the regime of low electron densities, concomitant with the development of strong spin- orbit interaction, magnetic order emerges.
Samuel Kenneth Davis; Zhen Huang; Kun Han; Ariando; Thirumalai Venkatesan; Venkat Chandrasekhar
Anisotropic superconductivity and frozen electronic states at the (111) LaAlO3/SrTiO3 interface Journal Article
In: Physical Review B, vol. 98, pp. 024504, 2018.
Abstract | Links | BibTeX | Tags: perovskite, Superconductivity
@article{davis_111_superconductivity_2017,
title = {Anisotropic superconductivity and frozen electronic states at the (111) LaAlO3/SrTiO3 interface},
author = {Samuel Kenneth Davis and Zhen Huang and Kun Han and Ariando and Thirumalai Venkatesan and Venkat Chandrasekhar},
url = {https://journals.aps.org/prb/abstract/10.1103/PhysRevB.98.024504},
doi = {https://doi.org/10.1103/PhysRevB.98.024504},
year = {2018},
date = {2018-07-09},
journal = {Physical Review B},
volume = {98},
pages = {024504},
abstract = {We report measurements of the superconducting properties of the two-dimensional (2D) gas that forms at the interface between LaAlO3 (LAO) and SrTiO3 (STO) in the (111) crystal orientation, a system that permits in situ tuning of carrier density and disorder by means of a back-gate voltage Vg. Like the (001) oriented LAO/STO interface, superconductivity at the (111) LAO/STO interface can be tuned by Vg. The 2D superconductivity in these (111) LAO/STO samples shows an in-plane anisotropy, being different along different interface crystal directions, and “remembers” the disorder landscape at which they are cooled through the superconducting transition. The low energy scale and other characteristics of this memory effect distinguish it from charge-trapping effects previously observed in (001) interface samples.},
keywords = {perovskite, Superconductivity},
pubstate = {published},
tppubtype = {article}
}
We report measurements of the superconducting properties of the two-dimensional (2D) gas that forms at the interface between LaAlO3 (LAO) and SrTiO3 (STO) in the (111) crystal orientation, a system that permits in situ tuning of carrier density and disorder by means of a back-gate voltage Vg. Like the (001) oriented LAO/STO interface, superconductivity at the (111) LAO/STO interface can be tuned by Vg. The 2D superconductivity in these (111) LAO/STO samples shows an in-plane anisotropy, being different along different interface crystal directions, and “remembers” the disorder landscape at which they are cooled through the superconducting transition. The low energy scale and other characteristics of this memory effect distinguish it from charge-trapping effects previously observed in (001) interface samples.
Samuel Kenneth Davis
Emergent Phenomena at the (111) LaAlO3/SrTiO3 Interface PhD Thesis
Department of Physics, Northwestern University, 2017.
Abstract | Links | BibTeX | Tags: Magnetism, perovskite, Superconductivity
@phdthesis{Davis2017c,
title = {Emergent Phenomena at the (111) LaAlO3/SrTiO3 Interface},
author = {Samuel Kenneth Davis},
url = {http://www.nano.northwestern.edu/wp-content/uploads/2018/02/Davis-Thesis.pdf},
year = {2017},
date = {2017-12-01},
school = {Department of Physics, Northwestern University},
abstract = {In his Nobel lecture Herbert Kroemer famously stated that “The interface is the device”. While he made this statement in the context of semiconducting heterostructures, it has proven to be just as relevant for more complex materials, such as the transition metal oxides. In particular, the 2-D conducting gas that forms at the interface between two transition metal oxides LaAlO3 and SrTiO3 (LAO/STO) has shown that a system containing a rich phase space of phenomena can arise from the interface of two relatively boring insulators. These phenomena include superconductivity, magnetism, gate tuned metal to insulator and superconductor to insulator transitions as well as evidence of large spin-orbit coupling at the interface. While the observation of these effects has produced more than a decade of fervent research on the LAO/STO interface, these previous efforts have focused mainly on the (001) crystal orientation of the LAO/STO interface. This thesis presents the results of some of the first studies on the (111) orientation of the LAO/STO interface, which not only has a more complex interfacial symmetry, but also shows new emergent phenomena. The most striking of which is the observation of strong, in-plane, anisotropy in the almost all of interface’s electrical transport properties. The thesis will identify not only identify where this anisotropy “lives” in the (111) LAO/STO interface, but also examine the energy scale at which it onsets. These results are evidence of an electronic nematic state that breaks the rotational symmetry of the sample. Finally, it will explore how this anisotropy impacts the other phenomena present at the interface, superconductivity and ferromagnetism.},
keywords = {Magnetism, perovskite, Superconductivity},
pubstate = {published},
tppubtype = {phdthesis}
}
In his Nobel lecture Herbert Kroemer famously stated that “The interface is the device”. While he made this statement in the context of semiconducting heterostructures, it has proven to be just as relevant for more complex materials, such as the transition metal oxides. In particular, the 2-D conducting gas that forms at the interface between two transition metal oxides LaAlO3 and SrTiO3 (LAO/STO) has shown that a system containing a rich phase space of phenomena can arise from the interface of two relatively boring insulators. These phenomena include superconductivity, magnetism, gate tuned metal to insulator and superconductor to insulator transitions as well as evidence of large spin-orbit coupling at the interface. While the observation of these effects has produced more than a decade of fervent research on the LAO/STO interface, these previous efforts have focused mainly on the (001) crystal orientation of the LAO/STO interface. This thesis presents the results of some of the first studies on the (111) orientation of the LAO/STO interface, which not only has a more complex interfacial symmetry, but also shows new emergent phenomena. The most striking of which is the observation of strong, in-plane, anisotropy in the almost all of interface’s electrical transport properties. The thesis will identify not only identify where this anisotropy “lives” in the (111) LAO/STO interface, but also examine the energy scale at which it onsets. These results are evidence of an electronic nematic state that breaks the rotational symmetry of the sample. Finally, it will explore how this anisotropy impacts the other phenomena present at the interface, superconductivity and ferromagnetism.
S. Davis; Z. Huang; K. Han; Ariando; T. Venkatesan; V. Chandrasekhar
Magnetoresistance in the superconducting state at the (111) LaAlO3/SrTiO3 interface Journal Article
In: Physical Review B, vol. 96, pp. 134502, 2017.
Abstract | Links | BibTeX | Tags: epitaxial, Magnetism, perovskite, Superconductivity
@article{Davis2017,
title = {Magnetoresistance in the superconducting state at the (111) LaAlO3/SrTiO3 interface},
author = {S. Davis and Z. Huang and K. Han and Ariando and T. Venkatesan and V. Chandrasekhar},
url = {https://journals.aps.org/prb/abstract/10.1103/PhysRevB.96.134502},
doi = {https://doi.org/10.1103/PhysRevB.96.134502},
year = {2017},
date = {2017-07-11},
journal = {Physical Review B},
volume = {96},
pages = {134502},
abstract = {Condensed-matter systems that simultaneously exhibit superconductivity and ferromagnetism are rare due the antagonistic relationship between conventional spin-singlet superconductivity and ferromagnetic order. In materials in which superconductivity and magnetic order are known to coexist (such as some heavy-fermion materials), the superconductivity is thought to be of an unconventional nature. Recently, the conducting gas that lives at the interface between the perovskite band insulators LaAlO3 (LAO) and SrTiO3 (STO) has also been shown to host both superconductivity and magnetism. Most previous research has focused on LAO/STO samples in which the interface is on the (001) crystal plane. Relatively little work has focused on the (111) crystal orientation, which has hexagonal symmetry at the interface, and has been predicted to have potentially interesting topological properties, including unconventional superconducting pairing states. Here we report measurements of the magnetoresistance of (111) LAO/STO heterostructures at temperatures at which they are also superconducting. As with the (001) structures, the magnetoresistance is hysteretic, indicating the coexistence of magnetism and superconductivity, but in addition, we find that this magnetoresistance is anisotropic. Such an anisotropic response is completely unexpected in the superconducting state and suggests that (111) LAO/STO heterostructures may support unconventional superconductivity.},
keywords = {epitaxial, Magnetism, perovskite, Superconductivity},
pubstate = {published},
tppubtype = {article}
}
Condensed-matter systems that simultaneously exhibit superconductivity and ferromagnetism are rare due the antagonistic relationship between conventional spin-singlet superconductivity and ferromagnetic order. In materials in which superconductivity and magnetic order are known to coexist (such as some heavy-fermion materials), the superconductivity is thought to be of an unconventional nature. Recently, the conducting gas that lives at the interface between the perovskite band insulators LaAlO3 (LAO) and SrTiO3 (STO) has also been shown to host both superconductivity and magnetism. Most previous research has focused on LAO/STO samples in which the interface is on the (001) crystal plane. Relatively little work has focused on the (111) crystal orientation, which has hexagonal symmetry at the interface, and has been predicted to have potentially interesting topological properties, including unconventional superconducting pairing states. Here we report measurements of the magnetoresistance of (111) LAO/STO heterostructures at temperatures at which they are also superconducting. As with the (001) structures, the magnetoresistance is hysteretic, indicating the coexistence of magnetism and superconductivity, but in addition, we find that this magnetoresistance is anisotropic. Such an anisotropic response is completely unexpected in the superconducting state and suggests that (111) LAO/STO heterostructures may support unconventional superconductivity.
Manan Mehta
Interplay between superconductivity and ferromagnetism at the LaAlO3/SrTiO3 interface PhD Thesis
2015.
Links | BibTeX | Tags: AMR, epitaxial, Kondo effect, Magnetic force microscopy, Magnetism, Mesoscopic quantum transport, scanning probe, Superconductivity, vortex dynamics
@phdthesis{Mehta2015,
title = {Interplay between superconductivity and ferromagnetism at the LaAlO3/SrTiO3 interface},
author = {Manan Mehta},
url = {http://www.nano.northwestern.edu/wp-content/uploads/2017/09/Manan_Mehta_PhD_Thesis.pdf},
year = {2015},
date = {2015-12-01},
keywords = {AMR, epitaxial, Kondo effect, Magnetic force microscopy, Magnetism, Mesoscopic quantum transport, scanning probe, Superconductivity, vortex dynamics},
pubstate = {published},
tppubtype = {phdthesis}
}
V. V. Bal; M. M. Mehta; S. Ryu; H. Lee; C. M. Folkman; C. B. Eom; V. Chandrasekhar
Gate-tunable superconducting weak link behavior in top-gated LaAlO3-SrTiO3 Journal Article
In: Applied Physics Letters, vol. 106, no. 21, pp. 212601, 2015.
Links | BibTeX | Tags: epitaxial, Magnetism, perovskite, Proximity effect, Superconductivity
@article{bal_gate-tunable_2015,
title = {Gate-tunable superconducting weak link behavior in top-gated LaAlO3-SrTiO3},
author = { V. V. Bal and M. M. Mehta and S. Ryu and H. Lee and C. M. Folkman and C. B. Eom and V. Chandrasekhar},
url = {http://scitation.aip.org/content/aip/journal/apl/106/21/10.1063/1.4921924},
year = {2015},
date = {2015-01-01},
urldate = {2016-12-28},
journal = {Applied Physics Letters},
volume = {106},
number = {21},
pages = {212601},
keywords = {epitaxial, Magnetism, perovskite, Proximity effect, Superconductivity},
pubstate = {published},
tppubtype = {article}
}
Taewan Noh; Sam Davis; Venkat Chandrasekhar
Nonlocal correlations in a proximity-coupled normal-metal Journal Article
In: Physical Review B, vol. 88, no. 2, 2013, ISSN: 1098-0121, 1550-235X.
Links | BibTeX | Tags: Andreev reflection, Proximity effect, Superconductivity
@article{noh_nonlocal_2013,
title = {Nonlocal correlations in a proximity-coupled normal-metal},
author = { Taewan Noh and Sam Davis and Venkat Chandrasekhar},
url = {http://link.aps.org/doi/10.1103/PhysRevB.88.024502},
doi = {10.1103/PhysRevB.88.024502},
issn = {1098-0121, 1550-235X},
year = {2013},
date = {2013-07-01},
urldate = {2016-12-28},
journal = {Physical Review B},
volume = {88},
number = {2},
keywords = {Andreev reflection, Proximity effect, Superconductivity},
pubstate = {published},
tppubtype = {article}
}
Taewan Noh; Manuel Houzet; Julia S. Meyer; Venkat Chandrasekhar
Nonlocal spin correlations mediated by a superconductor Journal Article
In: Physical Review B, vol. 87, no. 22, 2013, ISSN: 1098-0121, 1550-235X.
Links | BibTeX | Tags: Andreev reflection, Proximity effect, spin transport, Superconductivity
@article{noh_nonlocal_2013-1,
title = {Nonlocal spin correlations mediated by a superconductor},
author = { Taewan Noh and Manuel Houzet and Julia S. Meyer and Venkat Chandrasekhar},
url = {http://link.aps.org/doi/10.1103/PhysRevB.87.220502},
doi = {10.1103/PhysRevB.87.220502},
issn = {1098-0121, 1550-235X},
year = {2013},
date = {2013-06-01},
urldate = {2015-10-26},
journal = {Physical Review B},
volume = {87},
number = {22},
keywords = {Andreev reflection, Proximity effect, spin transport, Superconductivity},
pubstate = {published},
tppubtype = {article}
}
M.M. Mehta; D.A. Dikin; C.W. Bark; S. Ryu; C.M. Folkman; C.B. Eom; V. Chandrasekhar
Evidence for charge–vortex duality at the LaAlO3/SrTiO3 interface Journal Article
In: Nature Communications, vol. 3, pp. 955, 2012, ISSN: 2041-1723.
Links | BibTeX | Tags: epitaxial, insulator, Magnetism, perovskite, Superconductivity
@article{mehta_evidence_2012,
title = {Evidence for charge–vortex duality at the LaAlO3/SrTiO3 interface},
author = { M.M. Mehta and D.A. Dikin and C.W. Bark and S. Ryu and C.M. Folkman and C.B. Eom and V. Chandrasekhar},
url = {http://www.nature.com/doifinder/10.1038/ncomms1959},
doi = {10.1038/ncomms1959},
issn = {2041-1723},
year = {2012},
date = {2012-07-01},
urldate = {2015-10-23},
journal = {Nature Communications},
volume = {3},
pages = {955},
keywords = {epitaxial, insulator, Magnetism, perovskite, Superconductivity},
pubstate = {published},
tppubtype = {article}
}
Jian Wei; P. Cadden-Zimansky; V. Chandrasekhar; P. Virtanen
Thermal fluctuations and flux-tunable barrier in proximity Josephson junctions Journal Article
In: Physical Review B, vol. 84, no. 22, 2011, ISSN: 1098-0121, 1550-235X.
Links | BibTeX | Tags: Andreev reflection, Proximity effect, Superconductivity
@article{wei_thermal_2011,
title = {Thermal fluctuations and flux-tunable barrier in proximity Josephson junctions},
author = { Jian Wei and P. Cadden-Zimansky and V. Chandrasekhar and P. Virtanen},
url = {http://link.aps.org/doi/10.1103/PhysRevB.84.224519},
doi = {10.1103/PhysRevB.84.224519},
issn = {1098-0121, 1550-235X},
year = {2011},
date = {2011-12-01},
urldate = {2016-12-29},
journal = {Physical Review B},
volume = {84},
number = {22},
keywords = {Andreev reflection, Proximity effect, Superconductivity},
pubstate = {published},
tppubtype = {article}
}
D. A. Dikin; M. Mehta; C. W. Bark; C. M. Folkman; C. B. Eom; V. Chandrasekhar
Coexistence of Superconductivity and Ferromagnetism in Two Dimensions Journal Article
In: Physical Review Letters, vol. 107, no. 5, 2011, ISSN: 0031-9007, 1079-7114.
Links | BibTeX | Tags: epitaxial, Magnetism, perovskite, Superconductivity
@article{dikin_coexistence_2011,
title = {Coexistence of Superconductivity and Ferromagnetism in Two Dimensions},
author = { D. A. Dikin and M. Mehta and C. W. Bark and C. M. Folkman and C. B. Eom and V. Chandrasekhar},
url = {http://link.aps.org/doi/10.1103/PhysRevLett.107.056802},
doi = {10.1103/PhysRevLett.107.056802},
issn = {0031-9007, 1079-7114},
year = {2011},
date = {2011-07-01},
urldate = {2015-10-26},
journal = {Physical Review Letters},
volume = {107},
number = {5},
keywords = {epitaxial, Magnetism, perovskite, Superconductivity},
pubstate = {published},
tppubtype = {article}
}
Goutam Sheet; Manan Mehta; D. A. Dikin; S. Lee; C. W. Bark; J. Jiang; J. D. Weiss; E. E. Hellstrom; M. S. Rzchowski; C. B. Eom; V. Chandrasekhar
Phase-Incoherent Superconducting Pairs in the Normal State of Ba ( Fe 1 − x Co x ) 2 As 2 Journal Article
In: Physical Review Letters, vol. 105, no. 16, 2010, ISSN: 0031-9007, 1079-7114.
Links | BibTeX | Tags: Andreev reflection, Superconductivity
@article{sheet_phase-incoherent_2010,
title = {Phase-Incoherent Superconducting Pairs in the Normal State of Ba ( Fe 1 − x Co x ) 2 As 2},
author = { Goutam Sheet and Manan Mehta and D. A. Dikin and S. Lee and C. W. Bark and J. Jiang and J. D. Weiss and E. E. Hellstrom and M. S. Rzchowski and C. B. Eom and V. Chandrasekhar},
url = {http://link.aps.org/doi/10.1103/PhysRevLett.105.167003},
doi = {10.1103/PhysRevLett.105.167003},
issn = {0031-9007, 1079-7114},
year = {2010},
date = {2010-10-01},
urldate = {2016-12-28},
journal = {Physical Review Letters},
volume = {105},
number = {16},
keywords = {Andreev reflection, Superconductivity},
pubstate = {published},
tppubtype = {article}
}
Manan Mehta; Goutam Sheet; D. A. Dikin; S. Lee; C. W. Bark; J. Jiang; J. D. Weiss; E. E. Hellstrom; M. S. Rzchowski; C. B. Eom; V. Chandrasekhar
Conductance asymmetry in point-contacts on epitaxial thin films of Ba(Fe0.92Co0.08)2As2 Journal Article
In: Applied Physics Letters, vol. 97, no. 1, pp. 012503, 2010, ISSN: 0003-6951, 1077-3118.
Links | BibTeX | Tags: Andreev reflection, epitaxial, perovskite, Superconductivity
@article{mehta_conductance_2010,
title = {Conductance asymmetry in point-contacts on epitaxial thin films of Ba(Fe0.92Co0.08)2As2},
author = { Manan Mehta and Goutam Sheet and D. A. Dikin and S. Lee and C. W. Bark and J. Jiang and J. D. Weiss and E. E. Hellstrom and M. S. Rzchowski and C. B. Eom and V. Chandrasekhar},
url = {http://aip.scitation.org/doi/10.1063/1.3460274},
doi = {10.1063/1.3460274},
issn = {0003-6951, 1077-3118},
year = {2010},
date = {2010-07-01},
urldate = {2016-12-28},
journal = {Applied Physics Letters},
volume = {97},
number = {1},
pages = {012503},
keywords = {Andreev reflection, epitaxial, perovskite, Superconductivity},
pubstate = {published},
tppubtype = {article}
}
Jian Wei; Venkat Chandrasekhar
Positive noise cross-correlation in hybrid superconducting and normal-metal three-terminal devices Journal Article
In: Nature Physics, vol. 6, pp. 494-498, 2010.
Abstract | Links | BibTeX | Tags: Andreev reflection, crossed andreev reflection, Proximity effect, Superconductivity
@article{Wei2010,
title = {Positive noise cross-correlation in hybrid superconducting and normal-metal three-terminal devices},
author = {Jian Wei and Venkat Chandrasekhar},
url = {https://www.nature.com/articles/nphys1669},
doi = {https://doi.org/10.1038/nphys1669},
year = {2010},
date = {2010-05-16},
journal = {Nature Physics},
volume = {6},
pages = {494-498},
abstract = {Non-local entanglement is a key ingredient to quantum information processing. For photons, entanglement has been demonstrated, but it is more difficult to observe for electrons. One approach is to use a superconductor, where electrons form spin-entangled Cooper pairs, which is a natural source for entangled electrons. For a three-terminal device consisting of a superconductor sandwiched between two normal metals, it has been predicted that Cooper pairs can split into spin-entangled electrons flowing in the two spatially separated normal metals resulting in a negative non-local resistance and a positive current–current correlation. The former prosperity has been observed, but not the latter. Here we show that both characteristics can be observed, consistent with Cooper-pair splitting. Moreover, the splitting efficiency can be tuned by independently controlling the energy of the electrons passing the two superconductor/normal-metal interfaces, which may lead to better understanding and control of non-local entanglement.},
keywords = {Andreev reflection, crossed andreev reflection, Proximity effect, Superconductivity},
pubstate = {published},
tppubtype = {article}
}
Non-local entanglement is a key ingredient to quantum information processing. For photons, entanglement has been demonstrated, but it is more difficult to observe for electrons. One approach is to use a superconductor, where electrons form spin-entangled Cooper pairs, which is a natural source for entangled electrons. For a three-terminal device consisting of a superconductor sandwiched between two normal metals, it has been predicted that Cooper pairs can split into spin-entangled electrons flowing in the two spatially separated normal metals resulting in a negative non-local resistance and a positive current–current correlation. The former prosperity has been observed, but not the latter. Here we show that both characteristics can be observed, consistent with Cooper-pair splitting. Moreover, the splitting efficiency can be tuned by independently controlling the energy of the electrons passing the two superconductor/normal-metal interfaces, which may lead to better understanding and control of non-local entanglement.
Goutam Sheet; Venkat Chandrasekhar
Possible microscopic origin of large broadening parameter in point Andreev reflection spectroscopy Journal Article
In: Applied Physics Letters, vol. 97, no. 6, pp. 062507, 2010, ISSN: 0003-6951, 1077-3118.
Links | BibTeX | Tags: Andreev reflection, perovskite, point contact, Superconductivity
@article{sheet_possible_2010,
title = {Possible microscopic origin of large broadening parameter in point Andreev reflection spectroscopy},
author = { Goutam Sheet and Venkat Chandrasekhar},
url = {http://aip.scitation.org/doi/10.1063/1.3479927},
doi = {10.1063/1.3479927},
issn = {0003-6951, 1077-3118},
year = {2010},
date = {2010-01-01},
urldate = {2016-12-29},
journal = {Applied Physics Letters},
volume = {97},
number = {6},
pages = {062507},
keywords = {Andreev reflection, perovskite, point contact, Superconductivity},
pubstate = {published},
tppubtype = {article}
}
Venkat Chandrasekhar
Thermal transport in superconductor/normal-metal structures Journal Article
In: Supercond. Sci. Technol., vol. 22, no. 8, pp. 083001, 2009, ISSN: 0953-2048.
Links | BibTeX | Tags: Proximity effect, Superconductivity, thermal transport
@article{chandrasekhar_thermal_2009,
title = {Thermal transport in superconductor/normal-metal structures},
author = { Venkat Chandrasekhar},
url = {http://iopscience.iop.org/article/10.1088/0953-2048/22/8/083001/meta},
doi = {10.1088/0953-2048/22/8/083001},
issn = {0953-2048},
year = {2009},
date = {2009-07-01},
urldate = {2016-12-28},
journal = {Supercond. Sci. Technol.},
volume = {22},
number = {8},
pages = {083001},
keywords = {Proximity effect, Superconductivity, thermal transport},
pubstate = {published},
tppubtype = {article}
}
Paul Cadden-Zimansky; Jian Wei; Venkat Chandrasekhar
Cooper-pair-mediated coherence between two normal metals Journal Article
In: Nature Physics, vol. 5, pp. 393–397, 2009.
Abstract | Links | BibTeX | Tags: Andreev reflection, crossed andreev reflection, Proximity effect, Superconductivity
@article{Cadden-Zimansky2009,
title = {Cooper-pair-mediated coherence between two normal metals},
author = {Paul Cadden-Zimansky and Jian Wei and Venkat Chandrasekhar},
url = {https://www.nature.com/articles/nphys1252?foxtrotcallback=true},
doi = {https://doi.org/10.1038/nphys1252},
year = {2009},
date = {2009-04-26},
journal = {Nature Physics},
volume = {5},
pages = {393–397},
abstract = {Two electrons bound in a singlet state have long provided a conceptual and pedagogical framework for understanding the non-local nature of entangled quantum objects. As bound singlet electrons separated by a coherence length of up to several hundred nanometres occur naturally in conventional Bardeen–Cooper–Schrieffer superconductors in the form of Cooper pairs, recent theoretical investigations have focused on whether electrons in spatially separated normal-metal probes placed within a coherence length of each other on a superconductor can be quantum mechanically coupled by the singlet pairs. This coupling is predicted to occur through the non-local processes of elastic cotunnelling and crossed Andreev reflection. In crossed Andreev reflection, the constituent electrons of a Cooper pair are sent into different normal probes while retaining their mutual coherence. In elastic cotunnelling, a sub-gap electron approaching the superconductor from one normal probe undergoes coherent, long-range tunnelling to the second probe that is mediated by the Cooper pairs in the condensate. Here, we present experimental evidence for coherent, non-local coupling between electrons in two normal metals linked by a superconductor. The coupling is observed in non-local resistance oscillations that are periodic in an externally applied magnetic flux.},
keywords = {Andreev reflection, crossed andreev reflection, Proximity effect, Superconductivity},
pubstate = {published},
tppubtype = {article}
}
Two electrons bound in a singlet state have long provided a conceptual and pedagogical framework for understanding the non-local nature of entangled quantum objects. As bound singlet electrons separated by a coherence length of up to several hundred nanometres occur naturally in conventional Bardeen–Cooper–Schrieffer superconductors in the form of Cooper pairs, recent theoretical investigations have focused on whether electrons in spatially separated normal-metal probes placed within a coherence length of each other on a superconductor can be quantum mechanically coupled by the singlet pairs. This coupling is predicted to occur through the non-local processes of elastic cotunnelling and crossed Andreev reflection. In crossed Andreev reflection, the constituent electrons of a Cooper pair are sent into different normal probes while retaining their mutual coherence. In elastic cotunnelling, a sub-gap electron approaching the superconductor from one normal probe undergoes coherent, long-range tunnelling to the second probe that is mediated by the Cooper pairs in the condensate. Here, we present experimental evidence for coherent, non-local coupling between electrons in two normal metals linked by a superconductor. The coupling is observed in non-local resistance oscillations that are periodic in an externally applied magnetic flux.
Paul Cadden-Zimansky
Nonlocal Coherence in Normal Metal-Superconductor Nanostructures PhD Thesis
2008.
Links | BibTeX | Tags: Andreev reflection, charge imbalance, crossed andreev reflection, Mesoscopic quantum transport, nanomagnets, phase coherence, Proximity effect, Superconductivity
@phdthesis{Cadden-Zimansky2008,
title = {Nonlocal Coherence in Normal Metal-Superconductor Nanostructures},
author = {Paul Cadden-Zimansky},
url = {http://www.nano.northwestern.edu/wp-content/uploads/2017/09/C-Z-Thesis-Final.pdf},
year = {2008},
date = {2008-12-01},
keywords = {Andreev reflection, charge imbalance, crossed andreev reflection, Mesoscopic quantum transport, nanomagnets, phase coherence, Proximity effect, Superconductivity},
pubstate = {published},
tppubtype = {phdthesis}
}
Udai Raj Singh; Anjan K. Gupta; Goutam Sheet; Venkat Chandrasekhar; H. W. Jang; C. B. Eom
Pseudogap formation in the metallic state of La0.7Sr0.3MnO3 thin films Journal Article
In: Applied Physics Letters, vol. 93, no. 21, pp. 212503, 2008, ISSN: 0003-6951, 1077-3118.
Links | BibTeX | Tags: Andreev reflection, point contact, scanning probe, Superconductivity
@article{singh_pseudogap_2008,
title = {Pseudogap formation in the metallic state of La0.7Sr0.3MnO3 thin films},
author = { Udai Raj Singh and Anjan K. Gupta and Goutam Sheet and Venkat Chandrasekhar and H. W. Jang and C. B. Eom},
url = {http://aip.scitation.org/doi/10.1063/1.3028072},
doi = {10.1063/1.3028072},
issn = {0003-6951, 1077-3118},
year = {2008},
date = {2008-11-01},
urldate = {2016-12-28},
journal = {Applied Physics Letters},
volume = {93},
number = {21},
pages = {212503},
keywords = {Andreev reflection, point contact, scanning probe, Superconductivity},
pubstate = {published},
tppubtype = {article}
}
Venkat Chandrasekhar
An introduction to the quasiclassical theory of superconductivity for diffusive proximity-coupled systems Book Chapter
In: Karl-Heinz Bennemann; John B. Ketterson (Ed.): vol. Superconductivity: Volume 1, Springer Science & Business Media, 2008, ISBN: 978-3-540-73253-2, (Google-Books-ID: PguAgEQTiQwC).
Abstract | BibTeX | Tags: Andreev reflection, Proximity effect, Superconductivity
@inbook{bennemann_superconductivity:_2008,
title = {An introduction to the quasiclassical theory of superconductivity for diffusive proximity-coupled systems},
author = {Venkat Chandrasekhar},
editor = { Karl-Heinz Bennemann and John B. Ketterson},
isbn = {978-3-540-73253-2},
year = {2008},
date = {2008-04-01},
volume = { Superconductivity: Volume 1},
publisher = {Springer Science & Business Media},
abstract = {Conceived as the definitive reference in a classic and important field of modern physics, this extensive and comprehensive handbook systematically reviews the basic physics, theory and recent advances in the field of superconductivity. Leading researchers, including Nobel laureate, describe the state of the art in conventional and unconventional superconductors at a particularly opportune time, as new experimental techniques and field-theoretical methods have emerged. In addition to full-coverage of novel materials and underlying mechanisms, the handbook reflects continued intense research into electron-phone based superconductivity. Considerable attention is devoted to high-Tc superconductivity, novel superconductivity, including triplet pairing in the ruthenates, novel superconductors, such as Heavy-Fermion metals and organic materials, and also granular superconductors. What’s more, several contributions address superconductors with impurities and nanostructured superconductors. Important new results on current problems are presented in a manner designed to stimulate further research. Numerous illustrations, diagrams and tables make this book especially useful as a reference work for researchers, students and teachers. Treating the entire superconductivity field, this unparalleled reference resource carefully blends theoretical studies with experimental results to provide the scientist and engineers an indispensable foundation for further research.},
note = {Google-Books-ID: PguAgEQTiQwC},
keywords = {Andreev reflection, Proximity effect, Superconductivity},
pubstate = {published},
tppubtype = {inbook}
}
Conceived as the definitive reference in a classic and important field of modern physics, this extensive and comprehensive handbook systematically reviews the basic physics, theory and recent advances in the field of superconductivity. Leading researchers, including Nobel laureate, describe the state of the art in conventional and unconventional superconductors at a particularly opportune time, as new experimental techniques and field-theoretical methods have emerged. In addition to full-coverage of novel materials and underlying mechanisms, the handbook reflects continued intense research into electron-phone based superconductivity. Considerable attention is devoted to high-Tc superconductivity, novel superconductivity, including triplet pairing in the ruthenates, novel superconductors, such as Heavy-Fermion metals and organic materials, and also granular superconductors. What’s more, several contributions address superconductors with impurities and nanostructured superconductors. Important new results on current problems are presented in a manner designed to stimulate further research. Numerous illustrations, diagrams and tables make this book especially useful as a reference work for researchers, students and teachers. Treating the entire superconductivity field, this unparalleled reference resource carefully blends theoretical studies with experimental results to provide the scientist and engineers an indispensable foundation for further research.
J. Wei; P. Cadden-Zimansky; V. Chandrasekhar
Observation of large h∕2e and h∕4e oscillations in a proximity dc superconducting quantum interference device Journal Article
In: Applied Physics Letters, vol. 92, no. 10, pp. 102502, 2008, ISSN: 0003-6951, 1077-3118.
Links | BibTeX | Tags: Andreev reflection, Proximity effect, Superconductivity
@article{wei_observation_2008,
title = {Observation of large h∕2e and h∕4e oscillations in a proximity dc superconducting quantum interference device},
author = { J. Wei and P. Cadden-Zimansky and V. Chandrasekhar},
url = {http://aip.scitation.org/doi/10.1063/1.2894515},
doi = {10.1063/1.2894515},
issn = {0003-6951, 1077-3118},
year = {2008},
date = {2008-03-01},
urldate = {2016-12-29},
journal = {Applied Physics Letters},
volume = {92},
number = {10},
pages = {102502},
keywords = {Andreev reflection, Proximity effect, Superconductivity},
pubstate = {published},
tppubtype = {article}
}
P. Cadden-Zimansky; Z. Jiang; V. Chandrasekhar
Thermopower oscillation symmetries in a double-loop Andreev interferometer Journal Article
In: Physica E: Low-dimensional Systems and Nanostructures, vol. 40, no. 1, pp. 155–159, 2007, ISSN: 13869477.
Links | BibTeX | Tags: Andreev reflection, Proximity effect, Superconductivity, thermal transport
@article{cadden-zimansky_thermopower_2007,
title = {Thermopower oscillation symmetries in a double-loop Andreev interferometer},
author = { P. Cadden-Zimansky and Z. Jiang and V. Chandrasekhar},
url = {http://linkinghub.elsevier.com/retrieve/pii/S1386947707001282},
doi = {10.1016/j.physe.2007.05.023},
issn = {13869477},
year = {2007},
date = {2007-10-01},
urldate = {2016-12-29},
journal = {Physica E: Low-dimensional Systems and Nanostructures},
volume = {40},
number = {1},
pages = {155--159},
keywords = {Andreev reflection, Proximity effect, Superconductivity, thermal transport},
pubstate = {published},
tppubtype = {article}
}
P. Cadden-Zimansky; V. Chandrasekhar
Nonlocal Correlations in Normal-Metal Superconducting Systems Journal Article
In: Physical Review Letters, vol. 97, no. 23, 2006, ISSN: 0031-9007, 1079-7114.
Links | BibTeX | Tags: Andreev reflection, charge imbalance, crossed andreev reflection, Superconductivity
@article{cadden-zimansky_nonlocal_2006,
title = {Nonlocal Correlations in Normal-Metal Superconducting Systems},
author = { P. Cadden-Zimansky and V. Chandrasekhar},
url = {http://link.aps.org/doi/10.1103/PhysRevLett.97.237003},
doi = {10.1103/PhysRevLett.97.237003},
issn = {0031-9007, 1079-7114},
year = {2006},
date = {2006-12-01},
urldate = {2016-12-29},
journal = {Physical Review Letters},
volume = {97},
number = {23},
keywords = {Andreev reflection, charge imbalance, crossed andreev reflection, Superconductivity},
pubstate = {published},
tppubtype = {article}
}
Zhigang Jiang; José Aumentado; Wolfgang Belzig; Venkat Chandrasekhar
Transport through Ferromagnet/Superconductor Interfaces Journal Article
In: SpringerLink, pp. 57–66, 2006.
Links | BibTeX | Tags: Andreev reflection, charge imbalance, Magnetism, nanomagnets, Proximity effect, Superconductivity
@article{jiang_transport_2006,
title = {Transport through Ferromagnet/Superconductor Interfaces},
author = { Zhigang Jiang and José Aumentado and Wolfgang Belzig and Venkat Chandrasekhar},
url = {http://link.springer.com/chapter/10.1007/1-4020-4779-7_6},
doi = {10.1007/1-4020-4779-7_6},
year = {2006},
date = {2006-01-01},
urldate = {2016-12-28},
journal = {SpringerLink},
pages = {57--66},
keywords = {Andreev reflection, charge imbalance, Magnetism, nanomagnets, Proximity effect, Superconductivity},
pubstate = {published},
tppubtype = {article}
}
Zhigang Jiang; Venkat Chandrasekhar
Quantitative measurements of the thermal resistance of Andreev interferometers Journal Article
In: Physical Review B, vol. 72, pp. 020502(R), 2005.
Abstract | Links | BibTeX | Tags: Andreev reflection, Mesoscopic quantum transport, phase coherence, Proximity effect, Superconductivity
@article{Jiang2005b,
title = {Quantitative measurements of the thermal resistance of Andreev interferometers},
author = {Zhigang Jiang and Venkat Chandrasekhar},
url = {https://journals.aps.org/prb/abstract/10.1103/PhysRevB.72.020502},
doi = {https://doi.org/10.1103/PhysRevB.72.020502},
year = {2005},
date = {2005-07-08},
journal = {Physical Review B},
volume = {72},
pages = {020502(R)},
abstract = {Using a local thermometry technique, we have been able to quantitatively measure the thermal resistance RT of diffusive Andreev interferometers. We find that RT is strongly enhanced from its normal-state value at low temperatures, and behaves nonlinearly as a function of the thermal current through the sample. We also find that RT oscillates as a function of magnetic flux with a fundamental period corresponding to one flux quantum Φ0=h∕2e, demonstrating the phase-coherent nature of thermal transport in these devices. The magnitude of RT is larger than predicted by recent numerical simulations.},
keywords = {Andreev reflection, Mesoscopic quantum transport, phase coherence, Proximity effect, Superconductivity},
pubstate = {published},
tppubtype = {article}
}
Using a local thermometry technique, we have been able to quantitatively measure the thermal resistance RT of diffusive Andreev interferometers. We find that RT is strongly enhanced from its normal-state value at low temperatures, and behaves nonlinearly as a function of the thermal current through the sample. We also find that RT oscillates as a function of magnetic flux with a fundamental period corresponding to one flux quantum Φ0=h∕2e, demonstrating the phase-coherent nature of thermal transport in these devices. The magnitude of RT is larger than predicted by recent numerical simulations.
Zhigang Jiang
Thermal Transport Near the Normal-Metal/Superconductor Interface in Mesoscopic Devices PhD Thesis
2005.
Links | BibTeX | Tags: Andreev reflection, charge imbalance, Mesoscopic quantum transport, phase coherence, Proximity effect, Superconductivity
@phdthesis{Jiang2005,
title = {Thermal Transport Near the Normal-Metal/Superconductor Interface in Mesoscopic Devices},
author = {Zhigang Jiang},
url = {http://www.nano.northwestern.edu/wp-content/uploads/2017/09/JiangThesis.pdf},
year = {2005},
date = {2005-06-01},
keywords = {Andreev reflection, charge imbalance, Mesoscopic quantum transport, phase coherence, Proximity effect, Superconductivity},
pubstate = {published},
tppubtype = {phdthesis}
}
Z. Jiang; V. Chandrasekhar
Thermal Conductance of Andreev Interferometers Journal Article
In: Physical Review Letters, vol. 94, no. 14, 2005, ISSN: 0031-9007, 1079-7114.
Links | BibTeX | Tags: Andreev reflection, phase coherence, Proximity effect, Superconductivity, thermal transport
@article{jiang_thermal_2005,
title = {Thermal Conductance of Andreev Interferometers},
author = { Z. Jiang and V. Chandrasekhar},
url = {http://link.aps.org/doi/10.1103/PhysRevLett.94.147002},
doi = {10.1103/PhysRevLett.94.147002},
issn = {0031-9007, 1079-7114},
year = {2005},
date = {2005-04-01},
urldate = {2016-12-29},
journal = {Physical Review Letters},
volume = {94},
number = {14},
keywords = {Andreev reflection, phase coherence, Proximity effect, Superconductivity, thermal transport},
pubstate = {published},
tppubtype = {article}
}
Zhi-Gang Jiang; Venkat Chandrasekhar
The symmetry of phase-coherent thermopower oscillations in Andreev interferometers Journal Article
In: Chinese Journal of Physics, vol. 43, no. 3S, pp. 693–701, 2005.
Links | BibTeX | Tags: Andreev reflection, phase coherence, Proximity effect, Superconductivity, thermal transport
@article{jiang_symmetry_2005,
title = {The symmetry of phase-coherent thermopower oscillations in Andreev interferometers},
author = { Zhi-Gang Jiang and Venkat Chandrasekhar},
url = {http://www.airitilibrary.com/Publication/alDetailedMesh?docid=05779073-200506-201210080013-201210080013-693-701},
year = {2005},
date = {2005-01-01},
urldate = {2016-12-28},
journal = {Chinese Journal of Physics},
volume = {43},
number = {3S},
pages = {693--701},
keywords = {Andreev reflection, phase coherence, Proximity effect, Superconductivity, thermal transport},
pubstate = {published},
tppubtype = {article}
}
Z. Jiang; D. A. Dikin; V. Chandrasekhar; V. V. Metlushko; V. V. Moshchalkov
Pinning phenomena in a superconducting film with a square lattice of artificial pinning centers Journal Article
In: Applied physics letters, vol. 84, no. 26, pp. 5371–5373, 2004.
Links | BibTeX | Tags: Superconductivity, vortex dynamics
@article{jiang_pinning_2004,
title = {Pinning phenomena in a superconducting film with a square lattice of artificial pinning centers},
author = { Z. Jiang and D. A. Dikin and V. Chandrasekhar and V. V. Metlushko and V. V. Moshchalkov},
url = {http://scitation.aip.org/content/aip/journal/apl/84/26/10.1063/1.1767278},
year = {2004},
date = {2004-01-01},
urldate = {2016-12-29},
journal = {Applied physics letters},
volume = {84},
number = {26},
pages = {5371--5373},
keywords = {Superconductivity, vortex dynamics},
pubstate = {published},
tppubtype = {article}
}
J. Eom; J. Aumentado; V. Chandrasekhar; P.M. Baldo; L.E. Rehn
Superconducting proximity effect in the presence of strong spin scattering Journal Article
In: Solid State Communications, vol. 127, no. 8, pp. 545–549, 2003, ISSN: 00381098.
Links | BibTeX | Tags: Proximity effect, spin scattering, Superconductivity
@article{eom_superconducting_2003,
title = {Superconducting proximity effect in the presence of strong spin scattering},
author = { J. Eom and J. Aumentado and V. Chandrasekhar and P.M. Baldo and L.E. Rehn},
url = {http://linkinghub.elsevier.com/retrieve/pii/S0038109803004885},
doi = {10.1016/S0038-1098(03)00488-5},
issn = {00381098},
year = {2003},
date = {2003-08-01},
urldate = {2015-10-26},
journal = {Solid State Communications},
volume = {127},
number = {8},
pages = {545--549},
keywords = {Proximity effect, spin scattering, Superconductivity},
pubstate = {published},
tppubtype = {article}
}
D. A. Dikin; V. Chandrasekhar; V. R. Misko; V. M. Fomin; J. T. Devreese
Nucleation of superconductivity in mesoscopic star-shaped superconductors Journal Article
In: The European Physical Journal B - Condensed Matter, vol. 34, no. 2, pp. 231–235, 2003, ISSN: 1434-6028, 1434-6036.
Links | BibTeX | Tags: Superconductivity, vortex dynamics
@article{dikin_nucleation_2003,
title = {Nucleation of superconductivity in mesoscopic star-shaped superconductors},
author = { D. A. Dikin and V. Chandrasekhar and V. R. Misko and V. M. Fomin and J. T. Devreese},
url = {http://www.springerlink.com/Index/10.1140/epjb/e2003-00216-2},
doi = {10.1140/epjb/e2003-00216-2},
issn = {1434-6028, 1434-6036},
year = {2003},
date = {2003-07-01},
urldate = {2016-12-28},
journal = {The European Physical Journal B - Condensed Matter},
volume = {34},
number = {2},
pages = {231--235},
keywords = {Superconductivity, vortex dynamics},
pubstate = {published},
tppubtype = {article}
}
Z. Jiang; H. Lim; V. Chandrasekhar; J. Eom
Local thermometry technique based on proximity-coupled superconductor/normal-metal/superconductor devices Journal Article
In: Applied Physics Letters, vol. 83, no. 11, pp. 2190, 2003, ISSN: 00036951.
Links | BibTeX | Tags: Andreev reflection, Proximity effect, Superconductivity, thermal transport
@article{jiang_local_2003,
title = {Local thermometry technique based on proximity-coupled superconductor/normal-metal/superconductor devices},
author = { Z. Jiang and H. Lim and V. Chandrasekhar and J. Eom},
url = {http://scitation.aip.org/content/aip/journal/apl/83/11/10.1063/1.1611259},
doi = {10.1063/1.1611259},
issn = {00036951},
year = {2003},
date = {2003-01-01},
urldate = {2016-12-28},
journal = {Applied Physics Letters},
volume = {83},
number = {11},
pages = {2190},
keywords = {Andreev reflection, Proximity effect, Superconductivity, thermal transport},
pubstate = {published},
tppubtype = {article}
}
D. A. Dikin; S. Jung; V. Chandrasekhar
Low-temperature thermal properties of mesoscopic normal-metal/superconductor heterostructures Journal Article
In: Physical Review B, vol. 65, no. 1, 2001, ISSN: 0163-1829, 1095-3795.
Links | BibTeX | Tags: Andreev reflection, Proximity effect, Superconductivity, thermal transport
@article{dikin_low-temperature_2001,
title = {Low-temperature thermal properties of mesoscopic normal-metal/superconductor heterostructures},
author = { D. A. Dikin and S. Jung and V. Chandrasekhar},
url = {http://link.aps.org/doi/10.1103/PhysRevB.65.012511},
doi = {10.1103/PhysRevB.65.012511},
issn = {0163-1829, 1095-3795},
year = {2001},
date = {2001-12-01},
urldate = {2016-12-28},
journal = {Physical Review B},
volume = {65},
number = {1},
keywords = {Andreev reflection, Proximity effect, Superconductivity, thermal transport},
pubstate = {published},
tppubtype = {article}
}
D. A. Dikin; M. J. Black; V. Chandrasekhar
Magnetoresistance of Proximity-Coupled Au Wires Journal Article
In: Physical Review Letters, vol. 87, no. 18, 2001, ISSN: 0031-9007, 1079-7114.
Links | BibTeX | Tags: Andreev reflection, Proximity effect, Superconductivity
@article{dikin_magnetoresistance_2001,
title = {Magnetoresistance of Proximity-Coupled Au Wires},
author = { D. A. Dikin and M. J. Black and V. Chandrasekhar},
url = {http://link.aps.org/doi/10.1103/PhysRevLett.87.187003},
doi = {10.1103/PhysRevLett.87.187003},
issn = {0031-9007, 1079-7114},
year = {2001},
date = {2001-10-01},
urldate = {2015-10-23},
journal = {Physical Review Letters},
volume = {87},
number = {18},
keywords = {Andreev reflection, Proximity effect, Superconductivity},
pubstate = {published},
tppubtype = {article}
}
J. Aumentado; V. Chandrasekhar
Mesoscopic ferromagnet-superconductor junctions and the proximity effect Journal Article
In: Physical Review B, vol. 64, no. 5, 2001, ISSN: 0163-1829, 1095-3795.
Links | BibTeX | Tags: Andreev reflection, nanomagnets, Proximity effect, spin transport, Superconductivity
@article{aumentado_mesoscopic_2001,
title = {Mesoscopic ferromagnet-superconductor junctions and the proximity effect},
author = { J. Aumentado and V. Chandrasekhar},
url = {http://link.aps.org/doi/10.1103/PhysRevB.64.054505},
doi = {10.1103/PhysRevB.64.054505},
issn = {0163-1829, 1095-3795},
year = {2001},
date = {2001-07-01},
urldate = {2015-10-23},
journal = {Physical Review B},
volume = {64},
number = {5},
keywords = {Andreev reflection, nanomagnets, Proximity effect, spin transport, Superconductivity},
pubstate = {published},
tppubtype = {article}
}
Jonghwa Eom; Chen-Jung Chien; Venkat Chandrasekhar
Thermopower of Mesoscopic Normal-metal/Superconductor Heterostructures Journal Article
In: Journal of Low Temperature Physics, vol. 118, no. 5-6, pp. 617–635, 2000, ISSN: 0022-2291, 1573-7357.
Abstract | Links | BibTeX | Tags: Andreev reflection, Proximity effect, Superconductivity, thermal transport
@article{eom_thermopower_2000,
title = {Thermopower of Mesoscopic Normal-metal/Superconductor Heterostructures},
author = { Jonghwa Eom and Chen-Jung Chien and Venkat Chandrasekhar},
url = {http://link.springer.com.turing.library.northwestern.edu/article/10.1023/A:1004687210895},
doi = {10.1023/A:1004687210895},
issn = {0022-2291, 1573-7357},
year = {2000},
date = {2000-03-01},
urldate = {2016-12-28},
journal = {Journal of Low Temperature Physics},
volume = {118},
number = {5-6},
pages = {617--635},
abstract = {Measurements of micron-size doubly connected normal-Metal/superconductor (NS) heterostructures show athermoelectric response which oscillates as a function ofmagnetic field, with a fundamental period},
keywords = {Andreev reflection, Proximity effect, Superconductivity, thermal transport},
pubstate = {published},
tppubtype = {article}
}
Measurements of micron-size doubly connected normal-Metal/superconductor (NS) heterostructures show athermoelectric response which oscillates as a function ofmagnetic field, with a fundamental period
M. J. Black; V. Chandrasekhar
Influence of temperature-dependent inelastic scattering on the superconducting proximity effect Journal Article
In: EPL (Europhysics Letters), vol. 50, no. 2, pp. 257, 2000.
Links | BibTeX | Tags: Andreev reflection, Mesoscopic quantum transport, Proximity effect, Superconductivity
@article{black_influence_2000,
title = {Influence of temperature-dependent inelastic scattering on the superconducting proximity effect},
author = { M. J. Black and V. Chandrasekhar},
url = {http://iopscience.iop.org/0295-5075/50/2/257},
year = {2000},
date = {2000-01-01},
urldate = {2015-10-23},
journal = {EPL (Europhysics Letters)},
volume = {50},
number = {2},
pages = {257},
keywords = {Andreev reflection, Mesoscopic quantum transport, Proximity effect, Superconductivity},
pubstate = {published},
tppubtype = {article}
}
J. Eom; C.-J. Chien; V. Chandrasekhar
Thermoelectric effects in normal metal/superconductor interface structures Journal Article
In: Superlattices and Microstructures, vol. 25, no. 5-6, pp. 733–743, 1999, ISSN: 0749-6036.
Links | BibTeX | Tags: Andreev reflection, Proximity effect, Superconductivity, thermal transport
@article{eom_thermoelectric_1999,
title = {Thermoelectric effects in normal metal/superconductor interface structures},
author = { J. Eom and C.-J. Chien and V. Chandrasekhar},
url = {http://www.sciencedirect.com.turing.library.northwestern.edu/science/article/pii/S0749603699907358},
doi = {10.1006/spmi.1999.0735},
issn = {0749-6036},
year = {1999},
date = {1999-05-01},
urldate = {2016-12-28},
journal = {Superlattices and Microstructures},
volume = {25},
number = {5-6},
pages = {733--743},
keywords = {Andreev reflection, Proximity effect, Superconductivity, thermal transport},
pubstate = {published},
tppubtype = {article}
}
J. Aumentado; V. Chandrasekhar; J. Eom; P. M. Baldo; L. E. Rehn
Proximity effect thermometer for local electron temperature measurements on mesoscopic samples Journal Article
In: Applied physics letters, vol. 75, no. 22, pp. 3554–3556, 1999.
Links | BibTeX | Tags: Andreev reflection, Proximity effect, Superconductivity, thermal transport
@article{aumentado_proximity_1999,
title = {Proximity effect thermometer for local electron temperature measurements on mesoscopic samples},
author = { J. Aumentado and V. Chandrasekhar and J. Eom and P. M. Baldo and L. E. Rehn},
url = {http://scitation.aip.org/content/aip/journal/apl/75/22/10.1063/1.125386},
year = {1999},
date = {1999-01-01},
urldate = {2016-12-29},
journal = {Applied physics letters},
volume = {75},
number = {22},
pages = {3554--3556},
keywords = {Andreev reflection, Proximity effect, Superconductivity, thermal transport},
pubstate = {published},
tppubtype = {article}
}
C.-J. Chien; V. Chandrasekhar
Nonequilibrium transport in mesoscopic normal-metal–superconducting structures Journal Article
In: Physical Review B, vol. 60, no. 5, pp. 3655, 1999.
Links | BibTeX | Tags: Andreev reflection, Proximity effect, Superconductivity
@article{chien_nonequilibrium_1999,
title = {Nonequilibrium transport in mesoscopic normal-metal–superconducting structures},
author = { C.-J. Chien and V. Chandrasekhar},
url = {http://journals.aps.org/prb/abstract/10.1103/PhysRevB.60.3655},
year = {1999},
date = {1999-01-01},
urldate = {2016-12-28},
journal = {Physical Review B},
volume = {60},
number = {5},
pages = {3655},
keywords = {Andreev reflection, Proximity effect, Superconductivity},
pubstate = {published},
tppubtype = {article}
}
C.-J. Chien; V. Chandrasekhar
Reentrance effect in normal-metal/superconducting hybrid loops Journal Article
In: Physical Review B, vol. 60, no. 22, pp. 15356, 1999.
Links | BibTeX | Tags: Andreev reflection, Proximity effect, Superconductivity
@article{chien_reentrance_1999,
title = {Reentrance effect in normal-metal/superconducting hybrid loops},
author = { C.-J. Chien and V. Chandrasekhar},
url = {http://journals.aps.org/prb/abstract/10.1103/PhysRevB.60.15356},
year = {1999},
date = {1999-01-01},
urldate = {2016-12-29},
journal = {Physical Review B},
volume = {60},
number = {22},
pages = {15356},
keywords = {Andreev reflection, Proximity effect, Superconductivity},
pubstate = {published},
tppubtype = {article}
}
C. Strunk; Vital Bruyndoncx; Christian Van Haesendonck; V. V. Moshchalkov; Yvan Bruynseraede; C.-J. Chien; B. Burk; V. Chandrasekhar
Resistance anomalies in superconducting mesoscopic Al structures Journal Article
In: Physical Review B, vol. 57, no. 17, pp. 10854, 1998.
Links | BibTeX | Tags: charge imbalance, Superconductivity
@article{strunk_resistance_1998,
title = {Resistance anomalies in superconducting mesoscopic Al structures},
author = { C. Strunk and Vital Bruyndoncx and Christian Van Haesendonck and V. V. Moshchalkov and Yvan Bruynseraede and C.-J. Chien and B. Burk and V. Chandrasekhar},
url = {http://journals.aps.org/prb/abstract/10.1103/PhysRevB.57.10854},
year = {1998},
date = {1998-01-01},
urldate = {2016-12-29},
journal = {Physical Review B},
volume = {57},
number = {17},
pages = {10854},
keywords = {charge imbalance, Superconductivity},
pubstate = {published},
tppubtype = {article}
}
Jonghwa Eom; Chen-Jung Chien; Venkat Chandrasekhar
Phase dependent thermopower in Andreev interferometers Journal Article
In: Physical review letters, vol. 81, no. 2, pp. 437, 1998.
Links | BibTeX | Tags: Andreev reflection, Proximity effect, Superconductivity, thermal transport
@article{eom_phase_1998,
title = {Phase dependent thermopower in Andreev interferometers},
author = { Jonghwa Eom and Chen-Jung Chien and Venkat Chandrasekhar},
url = {http://journals.aps.org/prl/abstract/10.1103/PhysRevLett.81.437},
year = {1998},
date = {1998-01-01},
urldate = {2016-12-28},
journal = {Physical review letters},
volume = {81},
number = {2},
pages = {437},
keywords = {Andreev reflection, Proximity effect, Superconductivity, thermal transport},
pubstate = {published},
tppubtype = {article}
}
