Antiferromagnetic magnonic charge current generation via ultrafast optical excitation

TL;DR

This paper demonstrates the first experimental observation of ultrafast charge current generation in antiferromagnetic Mn2Au thin films via optical excitation, revealing a reciprocal process to Ne9el spin-orbit torque with potential for THz emission.

Contribution

It reports the experimental detection of magnonic charge currents in antiferromagnets induced by ultrafast optical pulses, a process previously unobserved.

Findings

Charge current generated in Mn2Au by ultrafast laser pulses

THz emission detected at room temperature

Magnonic charge current is reciprocal to Ne9el spin-orbit torque

Abstract

N\'eel spin-orbit torque allows a charge current pulse to efficiently manipulate the N\'eel vector in antiferromagnets, which offers a unique opportunity for ultrahigh density information storage with high speed. However, the reciprocal process of N\'eel spin-orbit torque, the generation of ultrafast charge current in antiferromagnets has not been demonstrated. Here, we report the experimental observation of charge current generation in antiferromagnetic metallic Mn2Au thin films using ultrafast optical excitation. The ultrafast laser pulse excites antiferromagnetic magnons, resulting in instantaneous non-equilibrium spin polarization at the antiferromagnetic spin sublattices with broken spatial symmetry. Then the charge current is generated directly via spin-orbit fields at the two sublattices, which is termed as the reciprocal phenomenon of N\'eel spin-orbit torque, and the associated THz emission can be detected at room temperature. Besides the fundamental significance on the Onsager reciprocity, the observed magnonic charge current generation in antiferromagnet would advance the development of antiferromagnetic THz emitter.