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Condensed Matter Seminar: Anand Bhattacharya, Argonne National Laboratory

Thu Sep 3, 2020 4:00PM - 5:00PM • Calendars: Condensed Matter Seminar

Some new findings in superconductivity in SrTiO3 and KTaO3 

Anand Bhattacharya, Argonne National Laboratory

The perovskite oxides SrTiO3 (STO) and KTaO(KTO) are both wide-bandgap perovskite insulators, on the verge of ferroelectricity. While STO can be doped readily into a metallic state, KTO is harder to dope in the bulk. Lightly doped STO is in fact a superconductor, with the earliest example of a 'dome' in the doping vs Tphase diagram. I will present some recent results, where we show that bulk STO is in fact superconducting at carrier densities far below previously thought, in a regime deep in the anti-adiabatic limit, though the superconductivity is inhomogeneous. In the second half of this talk, I shall discuss our recent discovery of superconductivity in 2-DEGs formed at (111) oriented interfaces of KTO. Here we find transition temperatures as high as 2.2 K, approximately an order of magnitude higher than in the very heavily studied 2DEGs formed at LaAlO3/SrTiO3 interfaces. Furthermore, in some of our 2DEGs we find that the superconductivity to be highly anisotropic, forming a 'stripe' like phase. I will try to explain what our findings might mean in light of our current understanding of superconductivity in this class of materials.

T. M. Bretz-Sullivan et al., arXiv: 1904.03121

C. Liu et al., arXiv: 2004.07416

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