Theory of the spin-galvanic effect and the anomalous phase shift φ0 in superconductors and Josephson junctions with intrinsic spin-orbit coupling

François Konschelle, Ilya V. Tokatly, and F. Sebastián Bergeret
Phys. Rev. B 92, 125443 – Published 30 September 2015

Abstract

Due to the spin-orbit coupling (SOC) an electric current flowing in a normal metal or semiconductor can induce a bulk magnetic moment. This effect is known as the Edelstein (EE) or magnetoelectric effect. Similarly, in a bulk superconductor a phase gradient may create a finite spin density. The inverse effect, also known as the spin-galvanic effect, corresponds to the creation of a supercurrent by an equilibrium spin polarization. Here, by exploiting the analogy between a linear-in-momentum SOC and a background SU(2) gauge field, we develop a quasiclassical transport theory to deal with magnetoelectric effects in superconducting structures. For bulk superconductors this approach allows us to easily reproduce and generalize a number of previously known results. For Josephson junctions we establish a direct connection between the inverse EE and the appearance of an anomalous phase shift φ0 in the current-phase relation. In particular we show that φ0 is proportional to the equilibrium spin current in the weak link. We also argue that our results are valid generically, beyond the particular case of linear-in-momentum SOC. The magnetoelectric effects discussed in this study may find applications in the emerging field of coherent spintronics with superconductors.

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  • Received 10 July 2015
  • Revised 3 August 2015

DOI:https://doi.org/10.1103/PhysRevB.92.125443

©2015 American Physical Society

Authors & Affiliations

François Konschelle1, Ilya V. Tokatly2,3, and F. Sebastián Bergeret1,4

  • 1Centro de Física de Materiales (CFM-MPC), Centro Mixto CSIC-UPV/EHU, Manuel de Lardizabal 4, E-20018 San Sebastián, Spain
  • 2Nano-Bio Spectroscopy Group, Departamento Física de Materiales, Universidad del País Vasco, Avenida Tolosa 72, E-20018 San Sebastián, Spain
  • 3IKERBASQUE, Basque Foundation for Science, E-48011 Bilbao, Spain
  • 4Donostia International Physics Center (DIPC), Manuel de Lardizabal 5, E-20018 San Sebastián, Spain

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Issue

Vol. 92, Iss. 12 — 15 September 2015

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