Dzyaloshinskii-Moriya-type interaction and Lifshitz invariant in Rashba 2D electron gas systems

TL;DR

This paper derives the Lifshitz invariant from the Rashba Hamiltonian in 2D electron gases, explaining the origin of chiral magnetic structures like skyrmions in ultrathin magnetic films.

Contribution

It establishes a theoretical link between Rashba spin-orbit coupling and Lifshitz invariants, elucidating the microscopic origin of chiral magnetic phenomena.

Findings

Lifshitz invariant can be derived from Rashba Hamiltonian in 2DEG.

Estimated spin cycloid period is about 10 nm, matching experimental observations.

Provides a microscopic basis for chiral magnetic structures in ultrathin films.

Abstract

The origin of chiral magnetic structures in ultrathin films of magnetic metals is analyzed. It is shown that the Lifshitz-type invariant term in the macroscopic thermodynamic potential can be derived from spin-orbit Rashba Hamiltonian in two dimensional electron gas (2DEG). The former is the prerequisite for existence of spin cycloid, skyrmions and other chiral phenomena observed in thin films. The estimation of the period of spin cycloid gives the value of an order of 10 nm that agrees well with the results of scanning probe microscopy observation reported in the literature.