Kadanoff Seminar: Pair spin-orbit interaction in Rashba materials. - Yasha Gindikin, University of Minnesota

We show that Rashba spin-orbit interaction (RSOI) modifies electron-electron interaction vertex giving rise to a spectrum of novel phenomena. First, the spin-orbit-modified Coulomb interactions induce p-wave superconducting order, without any need for other mediators of attraction. Remarkably, two distinct superconducting phases arise in 3D systems, mirroring the A or B phases of He3, depending on the sign of the SOI constant. In contrast, 2D systems exhibit $p^x \pm i p^y$ order parameter, leading to time-reversal-invariant topological superconductivity. Second, a sufficiently strong RSOI induces ferromagnetic ordering. It is associated with a deformation of the Fermi surface, which may lead to a Lifshitz transition from a spherical to a toroidal Fermi surface, with a number of experimentally observable signatures. Finally, in sufficiently clean Rashba materials, ferromagnetism and p-wave superconductivity may coexist. This state resembles the A1 phase of He3, yet it may avoid nodal points due to the toroidal shape of the Fermi surface.

[1]  Yasha Gindikin and Alex Kamenev, Electron interactions in Rashba materials, arXiv:2310.20084

[2]  Yasha Gindikin and Vladimir A. Sablikov, Spin-dependent electron-electron interaction in Rashba materials, Journal of Experimental and Theoretical Physics, 135, 4, 531 (2022).