Spin and orbital Edelstein effect in spin-orbit coupled noncentrosymmetric superconductor

TL;DR

This study explores how atomic spin-orbit coupling affects the spin and orbital Edelstein effects in noncentrosymmetric superconductors, revealing that orbital effects dominate and can be manipulated via orbital degrees of freedom.

Contribution

It provides a detailed analysis of the spin and orbital Edelstein effects in multiorbital superconductors, highlighting the roles of band structure and orbital characteristics in these magnetoelectric phenomena.

Findings

Orbital Edelstein effect is generally larger than spin Edelstein effect.

Sign of the orbital Edelstein effect remains robust near avoiding crossings.

Atomic spin-orbit coupling can significantly enhance the spin Edelstein effect.

Abstract

Superconductors without inversion symmetry can exhibit a non-zero magnetization when a supercurrent is present, leading to non-dissipative magnetoelectric effects. Here, we focus on understanding the relation between the spin and orbital properties of these effects in conventional spin-singlet noncentrosymmetric superconductors with orbital Rashba coupling, particularly for multiorbital electronic systems with coupled spin and orbital moments. We investigate how atomic spin-orbit coupling influences the magnitude and direction of the spin and orbital Edelstein effect. Our findings indicate that the correlation between spin and orbital moments induced by supercurrents is generally not determined by the sign of atomic spin-orbit coupling, but rather by the number of bands at the Fermi level and the orbital characteristics of those bands with respect to the mirror parity. We investigate the character of the spin and orbital Edelstein effect by examining its dependence in momentum space and the role of avoiding crossings in determining the induced magnetization. The outcomes demonstrate that the sign change of the orbital Edelstein effect near avoiding crossing bands remains robust despite modifications to the atomic spin-orbit amplitude. Furthermore, we observe that the spin Edelstein effect is typically one order of magnitude smaller than the orbital Edelstein effect, but can be significantly enhanced in certain scenarios with increased atomic spin-orbit coupling. These results indicate that by manipulating the orbital degrees of freedom in noncentrosymmetric materials, the relationship between the spin and orbital Edelstein moments can be effectively controlled.