Reversing Neel Vector in PT-Antiferromagnets by Nonreciprocal Light Scattering

Abstract: Antiferromagnetic (AFM) spintronics has been receiving tremendous attention due to their ultrafast kinetics, zero stray field, immune to external magnetic field, and potential to minimizing magnetic storage devices. The optical control of AFM Neel vector has become a hectic topic during recent years, which could facilitate the AFM utilization in practical systems. In this work, we propose a nonreciprocal light scattering mechanism to flip the Neel vector in parity-time (PT) combined AFM multilayers, by estimating the energy contrast between the bistable Neel polarization configurations. We illustrate our theory using a low energy kp model, and perform ab initio calculations on two typical A-type AFM materials, MnBi2Te4 and CrI3 thin films. We show that varying incident photon frequency could modulate the relative stability between the bistable Neel vector state, which also depends on the light handedness. According to this theory, our parameter-independent calculations on the Neel vector diagram shows consistent predictive results with recent experimental observations. This mechanism provides an effective route to controlling the AFM order parameter through photo-magnetic interaction.