Spatial trends of non-collinear exchange coupling mediated by itinerant carriers with different Fermi surfaces

TL;DR

This paper investigates how the exchange coupling mediated by itinerant carriers with spin-orbit interaction varies spatially, depending on Fermi surface topology, revealing different behaviors in weak and strong coupling regimes.

Contribution

It provides a combined analytic and numeric analysis of non-collinear exchange coupling influenced by Fermi surface topology and spin relaxation effects.

Findings

Exchange coupling is similar to RKKY in weak coupling.

Strong coupling leads to dominant spiral interactions.

Finite spin relaxation enhances non-collinear spiral interactions.

Abstract

We study the exchange coupling mediated by itinerant carriers with spin-orbit interaction by both analytic and numeric approaches. The mediated exchange coupling is non-collinear and its spatial trends depend on the Fermi surface topology of the itinerant carriers. Taking Rashba interaction as an example, the exchange coupling is similar to the conventional Ruderman-Kittel-Kasuya-Yosida type in weak coupling. On the other hand, in the strong coupling, the spiral interaction dominates. In addition, inclusion of finite spin relaxation always makes the non-collinear spiral exchange interaction dominant. Potential applications of our findings are explained and discussed.