Publications

@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}

}

@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}

}

@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}

}

@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}

}

@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}

}

@article{cadden-zimansky_coherent_2012,

title = {Coherent nonlocal correlations in Andreev interferometers},

author = { P Cadden-Zimansky and J Wei and V Chandrasekhar},

url = {http://stacks.iop.org/1367-2630/14/i=4/a=043004?key=crossref.f07cad531c95baf1d401aa858682bf05},

doi = {10.1088/1367-2630/14/4/043004},

issn = {1367-2630},

year  = {2012},

date = {2012-01-01},

urldate = {2016-12-28},

journal = {New Journal of Physics},

volume = {14},

number = {4},

pages = {043004},

keywords = {Andreev reflection, Proximity effect, superconductor},

pubstate = {published},

tppubtype = {article}

}

@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}

}

@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}

}

@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}

}

@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}

}

@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}

}

@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}

}

@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}

}

@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}

}

@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}

}

@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}

}

@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}

}

@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}

}

@article{dikin_quantitative_2002,

title = {Quantitative measurements of the thermopower of Andreev interferometers},

author = { D. A. Dikin and S. Jung and V. Chandrasekhar},

url = {http://iopscience.iop.org/article/10.1209/epl/i2002-00499-9/meta},

doi = {10.1209/epl/i2002-00499-9},

issn = {0295-5075},

year  = {2002},

date = {2002-01-01},

urldate = {2016-12-28},

journal = {EPL},

volume = {57},

number = {4},

pages = {564},

keywords = {Andreev reflection, phase coherence, Proximity effect, thermal transport},

pubstate = {published},

tppubtype = {article}

}

@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}

}

@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}

}

@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}

}

@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}

}

@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}

}

@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}

}

@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}

}

@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}

}

@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}

}

@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}

}