N\'{e}el Spin Orbit Torque driven antiferromagnetic resonance in Mn$_{2}$Au probed by time-domain THz spectroscopy

TL;DR

This study demonstrates that N{é}el spin-orbit torques can excite antiferromagnetic resonance in Mn₂Au, with strong THz absorption that varies with temperature, highlighting potential for ultrafast memory devices.

Contribution

It provides experimental evidence of N{é}el spin-orbit torque-driven antiferromagnetic resonance in Mn₂Au using time-domain THz spectroscopy, supported by theoretical modeling.

Findings

Observed a strong THz absorption mode near 1 THz that softens with temperature.

The mode is identified as an in-plane antiferromagnetic resonance (AFMR).

The AFMR absorption exceeds that in insulators by three orders of magnitude.

Abstract

We observe the excitation of collective modes in the THz range driven by the recently discovered N\'{e}el spin-orbit torques (NSOT) in the metallic antiferromagnet Mn$_{2}$Au. Temperature dependent THz spectroscopy reveals a strong absorption mode centered near 1 THz, which upon heating from 4 K to 450 K softens and looses intensity. Comparison with the estimated eigenmode frequencies implies that the observed mode is an in-plane antiferromagnetic resonance (AFMR) mode. The AFMR absorption strength exceeds those found in antiferromagnetic insulators, driven by the magnetic field of the THz radiation, by three orders of magnitude. Based on this and the agreement with our theory modelling, we infer that the driving mechanism for the observed mode is the current induced NSOT. This electric manipulation of the Ne\'{e}l order parameter at high frequencies makes Mn$_{2}$Au a prime candidate for AFM ultrafast memory applications.