Spin textures and spin-wave excitations in doped Dirac-Weyl semimetals

TL;DR

This paper investigates how doped Dirac-Weyl semimetals exhibit anisotropic spin correlations and spin-wave excitations due to spin-momentum locking, revealing potential for topologically nontrivial magnetic textures.

Contribution

It introduces an effective field theory capturing magnetic textures in doped Dirac-Weyl semimetals, highlighting anisotropic correlations and novel magnetic excitations.

Findings

Spin correlations are strongly anisotropic due to spin-momentum locking.

Topologically nontrivial magnetic textures like hedgehog states can form.

Spin-wave dispersion is anisotropic, with less dispersion perpendicular to magnetization.

Abstract

We study correlations and magnetic textures of localized spins, doped in three-dimensional Dirac semimetals. An effective field theory for magnetic moments is constructed by integrating out the fermionic degrees of freedom. The spin correlation shows a strong anisotropy, originating from spin-momentum locking of Dirac electrons, in addition to the conventional Heisenberg-like ferromagnetic correlation. The anisotropic spin correlation allows topologically nontrivial magnetic excitation textures such as a transient hedgehog state, as well as the ferromagnetic ground state. The spin-wave dispersion in ferromagnetic Weyl semimetal also becomes anisotropic, being less dispersed perpendicular to the magnetization.