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

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 E0 leads, through exchange-interaction modulation, to the dc and second-order harmonic spin currents proportional to E20. We also show that dc and ac staggered magnetic fields B0 generate the dc and ac spin currents proportional to B0, respectively. We elucidate the mechanism by an exactly solvable model, and thereby propose the ways of spin current manipulation by electromagnetic fields.