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Title: Superconducting Tunneling Spectroscopy of Spin-Orbit Coupling and Orbital Depairing in Nb : SrTiO 3

Abstract

We have examined here the intrinsic spin-orbit coupling and orbital depairing in thin films of Nb-doped $${\mathrm{SrTiO}}_{3}$$ 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 $${{\tau}}_{\mathrm{so}}{\le}1.1\text{ }\text{ }\mathrm{ps}$$. 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 $${\mathrm{SrTiO}}_{3}$$ is comparable to those associated with Rashba effects in $${\mathrm{SrTiO}}_{3}$$ interfacial conducting layers and can be considered significant in all forms of superconductivity in $${\mathrm{SrTiO}}_{3}$$.

Authors:
 [1];  [2];  [1];  [1];  [3];  [4];  [1]
  1. Stanford Univ., CA (United States). Geballe Lab. for Advanced Materials. Dept. of Applied Physics; SLAC National Accelerator Lab., Menlo Park, CA (United States). Stanford Inst. for Materials and Energy Sciences
  2. Stanford Univ., CA (United States). Dept. of Physics
  3. SLAC National Accelerator Lab., Menlo Park, CA (United States). Stanford Inst. for Materials and Energy Sciences
  4. SLAC National Accelerator Lab., Menlo Park, CA (United States). Stanford Inst. for Materials and Energy Sciences; Stanford Univ., CA (United States). Dept. of Physics
Publication Date:
Research Org.:
SLAC National Accelerator Lab., Menlo Park, CA (United States); Stanford Univ., CA (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22); Gordon and Betty Moore Foundation (United States)
OSTI Identifier:
1490400
Alternate Identifier(s):
OSTI ID: 1478591
Grant/Contract Number:  
AC02-76SF00515; GBMF4415
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Physical Review Letters
Additional Journal Information:
Journal Volume: 121; Journal Issue: 16; Journal ID: ISSN 0031-9007
Publisher:
American Physical Society (APS)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; coherence length; conductivity; density of states; electronic structure; multiband superconductivity; pseudogap; Rashba coupling; spin diffusion; spin-orbit coupling; superconducting gap; interfaces; multilayer thin films; tunnel junctions; ultrathin films

Citation Formats

Swartz, Adrian G., Cheung, Alfred K. C., Yoon, Hyeok, Chen, Zhuoyu, Hikita, Yasuyuki, Raghu, Srinivas, and Hwang, Harold Y. Superconducting Tunneling Spectroscopy of Spin-Orbit Coupling and Orbital Depairing in Nb:SrTiO3. United States: N. p., 2018. Web. doi:10.1103/physrevlett.121.167003.
Swartz, Adrian G., Cheung, Alfred K. C., Yoon, Hyeok, Chen, Zhuoyu, Hikita, Yasuyuki, Raghu, Srinivas, & Hwang, Harold Y. Superconducting Tunneling Spectroscopy of Spin-Orbit Coupling and Orbital Depairing in Nb:SrTiO3. United States. doi:10.1103/physrevlett.121.167003.
Swartz, Adrian G., Cheung, Alfred K. C., Yoon, Hyeok, Chen, Zhuoyu, Hikita, Yasuyuki, Raghu, Srinivas, and Hwang, Harold Y. Fri . "Superconducting Tunneling Spectroscopy of Spin-Orbit Coupling and Orbital Depairing in Nb:SrTiO3". United States. doi:10.1103/physrevlett.121.167003. https://www.osti.gov/servlets/purl/1490400.
@article{osti_1490400,
title = {Superconducting Tunneling Spectroscopy of Spin-Orbit Coupling and Orbital Depairing in Nb:SrTiO3},
author = {Swartz, Adrian G. and Cheung, Alfred K. C. and Yoon, Hyeok and Chen, Zhuoyu and Hikita, Yasuyuki and Raghu, Srinivas and Hwang, Harold Y.},
abstractNote = {We have examined here the intrinsic spin-orbit coupling and orbital depairing in thin films of Nb-doped ${\mathrm{SrTiO}}_{3}$ 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 ${{\tau}}_{\mathrm{so}}{\le}1.1\text{ }\text{ }\mathrm{ps}$. 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 ${\mathrm{SrTiO}}_{3}$ is comparable to those associated with Rashba effects in ${\mathrm{SrTiO}}_{3}$ interfacial conducting layers and can be considered significant in all forms of superconductivity in ${\mathrm{SrTiO}}_{3}$.},
doi = {10.1103/physrevlett.121.167003},
journal = {Physical Review Letters},
issn = {0031-9007},
number = 16,
volume = 121,
place = {United States},
year = {2018},
month = {10}
}

Journal Article:
Free Publicly Available Full Text
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Figures / Tables:

FIG. 1 FIG. 1: a) Schematic of the tunneling junction device structure and atomic stacking of the oxide heterostructure. b) Expected effect of Zeeman splitting on the spin-dependent DOS for two cases: zero spin-orbit coupling (b = 0) (left panel) and large spin-orbit coupling (b = 6) (right panel). The dimensionless SOCmore » parameter b = $h̄$/(3$τ$so$∆$0) reflects the strength of the SOC relative to the gap energy scale. Dashed blue (dashed grey) and solid red (solid grey) curves represent the spin-up and spin-down DOS, respectively, while the solid black curve gives the total DOS from $ρ$+$ρ$ (shifted upwards by 1 for clarity). The spectra were calculated using Maki’s theory (Eq. (2)) at $T$ = 0 K, lifetime broadening parameter $ζ$ = 0.1, and magnetic field $µ$B$H$/$∆$0 = 0.6.« less

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