Generation of dc, ac, and second-harmonic spin currents by electromagnetic fields in an inversion-asymmetric antiferromagnet

TL;DR

This paper theoretically demonstrates how electromagnetic fields can generate and manipulate dc, ac, and second-harmonic spin currents in an inversion-asymmetric antiferromagnet, advancing spintronics technology.

Contribution

It introduces a simple quantum antiferromagnet model showing how electric and magnetic fields induce various spin currents, with explicit mechanisms and potential control methods.

Findings

Electric fields induce dc and second-harmonic spin currents proportional to E_0^2.

Magnetic fields generate dc and ac spin currents proportional to B_0.

Exact solutions elucidate the mechanisms of spin current generation and manipulation.

Abstract

Manipulating spin currents in magnetic insulators is a key technology in spintronics. We theoretically study a simple inversion-asymmetric model of quantum antiferromagnets, where both the exchange interaction and the magnetic field are staggered. We calculate spin currents generated by external electric and magnetic fields by using a quantum master equation. We show that an ac electric field with amplitude $E_0$ leads, through exchange-interaction modulation, to the dc and second-harmonic spin currents proportional to $E_0^2$. We also show that dc and ac staggered magnetic fields $B_0$ generate the dc and ac spin currents proportional to $B_0$, respectively. We elucidate the mechanism by an exactly solvable model, and thereby propose the ways of spin current manipulation by electromagnetic fields.