"Superconducting Tunneling Spectroscopy of Spin-Orbit Coupling and Orbital Depairing in Nb : SrTiO3"

Adrian G. Swartz: Alfred K. C. Cheung, Hyeok Yoon, Zhuoyu Chen, Yasuyuki Hikita, Srinivas Raghu, and Harold Y. Hwang; Physical Review Letters, 10/19/18.

Additional Authors: Alfred K. C. Cheung, Hyeok Yoon, Zhuoyu Chen, Yasuyuki Hikita, Srinivas Raghu, and Harold Y. Hwang

Abstract:

We have examined the intrinsic spin-orbit coupling and orbital depairing in thin films of Nb-doped SrTiO3 by superconducting tunneling spectroscopy. The orbital depairing is geometrically suppressed in the two-dimensional limit, enabling a quantitative evaluation of the Fermi level spin-orbit scattering using Maki’s theory. The response of the superconducting gap under in-plane magnetic fields demonstrates short spin-orbit scattering times τso≤1.1  ps. Analysis of the orbital depairing indicates that the heavy electron band contributes significantly to pairing. These results suggest that the intrinsic spin-orbit scattering time in SrTiO3 is comparable to those associated with Rashba effects in SrTiO3 interfacial conducting layers and can be considered significant in all forms of superconductivity in SrTiO3.