Chiral spin ordering of electron gas in solids with broken time reversal symmetry

Abstract

In this work we manifest that an electrostatic disorder in conducting systems with broken time reversal symmetry universally leads to a chiral ordering of the electron gas giving rise to skyrmion-like textures in spatial distribution of the electron spin density. We describe a microscopic mechanism underlying the formation of the equilibrium chiral spin textures in two-dimensional systems with spin-orbit interaction and exchange spin splitting. We have obtained analytical expressions for spin-density response functions and have analyzed both local and non-local spin response to electrostatic perturbations for systems with parabolic-like and Dirac electron spectra. With the proposed theory we come up with a concept of controlling spin chirality by electrical means.

Electric field effect on electron gas spins in two-dimensional magnets with strong spin-orbit coupling

“…We note that the terms χ t and χ d are generally of the same order of magnitude. Moreover, in case when the electron gas populates both spin subbands µ > Ω 0 /2 the overall response entirely disappears χ t + χ d = 0 (this feature was previously noted by [59,66]). In the opposite case when electrons fill only the lowest spin-subband µ < Ω 0 /2 the terms χ t , χ d have opposite signs, which results in the 𝜉 = 0.6 sign-altering dependence of χ on the Fermi energy.…”

“…In the appendix A we present the connection of our method with the wave-packet quasiclassical technique used in [39][40][41]. In the appendix B we relate δs η k , δS η k to the Kubo formula method for the charge-spin correlation functions used in [59]. In particular, we show that the non-adiabatic spin precession is described by the interband correlation functions, while the spin-dipole effect stems from the intraband ones.…”

“…1. In [59] we used the Kubo formalism to address the nonlocal regime of the spin density response due to short-range impurities. In this section, instead, we provide a detailed semiclassical description of this phenomenon and accompany it by the comprehensive physical analysis.…”

“…In this appendix we relate the semiclassical description of magnetoelectric susceptibility in terms of the density matrix with the Kubo formula for the charge-spin correlation functions, considered in detail in [59]. The spin density induced in 2DEG by the change in the potential energy U (r) is given in linear response by…”

Friedel Oscillations Induced by Magnetic Skyrmions: From Scattering Properties to All-Electrical Detection

“…Interestingly, model calculations indicated that skyrmion-like magnetic Friedel oscillations can be induced by an adatom deposited on a surface characterized by a finite spin-orbit interaction [ 5 ] with a magnetic complexity that is detectable experimentally [ 52 ]. While free electrons scattering at skyrmions could carry a spin-magnetization of chiral nature [ 53 ], topological surface states can trigger interesting physics when eventually hitting a skyrmion [ 54 ].…”