Regular Article

Nonuniform superconductivity in wires with strong spin-orbit coupling

¹ Univ. Bordeaux, CNRS, LOMA, UMR 5798, 33405 Talence, France
² Donostia International Physics Center (DIPC), Manuel de Lardizabal 5, 20018 San Sebastián, Spain

^a e-mail: jerome.cayssol@u-bordeaux.fr

Received: 25 May 2020
Received in final form: 26 May 2020
Published online: 13 July 2020

Abstract

We study theoretically the onset of nonuniform superconductivity in a one-dimensional single wire in presence of Zeeman (or exchange field) and spin-orbit coupling. Using the Green’s function formalism, we show that the spin-orbit coupling stabilizes modulated superconductivity in a broad range of temperatures and Zeeman fields. We investigate the anisotropy of the temperature-Zeeman field phase diagram, which is related to the orientation of the Zeeman field. In particular, the inhomogeneous superconducting state disappears if this latter field is aligned or perpendicular to the wire direction. We identify two regimes corresponding to weak and strong spin-orbit coupling respectively. The wave-vector of the modulated phase is evaluated in both regimes. The results also pertain for quasi-1D superconductors made of weakly coupled 1D chains.