Low density superconductivity of SrTiO<sub>3</sub> bounded by the adiabatic condition

ORAL

Abstract

The dilute oxide semiconductor SrTiO3 exhibits superconductivity over a wide range of carrier densities (1017-1021 cm-3) lying outside of the Bardeen-Cooper-Schrieffer (BCS) and Migdal-Eliashberg theories for conventional superconductors. Across this range, the Fermi level traverses a variety of vibrational modes in the system and therefore spans the widest range of adiabatic parameter (ω/EF) of any superconductor, making it an ideal choice to study the physics of dilute superconductivity. Recently, we have developed an approach using atomically controlled oxide heterostructures to spectroscopically probe the electronic structure of SrTiO3 using planar tunneling junctions [1, 2]. Using this technique, we have examined the superconductivity of bulk doped SrTiO3 across the superconducting dome and found that superconducting state is bounded by the adiabatic condition, maintaining the thermodynamic relationship of BCS weak-coupling theory (2Δ/kBTc = 3.53).

[1] T. Yajima et al., Nano Lett. 15, 1622 (2015)
[2] A. G. Swartz, H. Inoue et al., Proc. Natl. Acad. Sci. USA 115, 1475 (2018)

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Presenters

  • Hyeok Yoon

    • Geballe Laboratory for Advanced Materials, Department of Applied Physics, Stanford University

Authors

  • Hyeok Yoon

    • Geballe Laboratory for Advanced Materials, Department of Applied Physics, Stanford University

  • Adrian G Swartz

    • Geballe Laboratory for Advanced Materials, Department of Applied Physics, Stanford University

  • Hisashi Inoue

    • Massachusetts Institute of Technology
    • Geballe Laboratory for Advanced Materials, Department of Applied Physics, Stanford University

  • Yasuyuki Hikita

    • Stanford Institute for Material and Energy Sciences, SLAC National Accelerator Laboratory
    • SIMES, SLAC National Accelerator Lab
    • Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory

  • Harold Hwang

    • Applied Physics, Stanford University
    • SIMES, SLAC National Accelerator Lab
    • Geballe Laboratory for Advanced Materials, Department of Applied Physics, Stanford University