Publications

@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}

}