Symmetry and the macroscopic dynamics of antiferromagnetic materials in the presence of spin-polarized current

TL;DR

This paper extends the theory of antiferromagnetic dynamics to include spin-polarized currents, predicting phenomena like current-induced reorientation, resonance, spin-diode effect, and second-harmonic generation in AFMs.

Contribution

It introduces a generalized theoretical framework for AFM dynamics under spin-polarized currents, applicable to inhomogeneous AFMs and predicting new current-induced effects.

Findings

Predicted current-induced reorientation and AFM resonance.

Derived critical currents based on AFMR frequencies and damping.

Demonstrated the possibility of spin-diode effect and second-harmonic generation.

Abstract

Antiferromagnetic (AFM) materials with zero or vanishingly small macroscopic magnetization are nowadays the constituent elements of spintronic devices. However, possibility to use them as active elements that show nontrivial controllable magnetic dynamics is still discussible. In the present paper we extend the theory [A.F.Andreev, V.I.Marchenko, Sov. Phys. --- Uspekhi, 23 (1980), 21] of macroscopic dynamics in AFMs for the cases typical for spin-valve devices. In particular, we consider the solid-like magnetic dynamics of AFMs with strong exchange coupling in the presence of spin-polarized current and give an expression for the current-induced Rayleigh dissipation function in terms of the rotation vector for different types %generalized potential of AFMs. Basing on the analysis of linearized equations of motion we predict the current-induced reorientation and AFM resonance, and found the values of critical currents in terms of AFMR frequencies and damping constants. We show the possibility of current-induced spin-diode effect and second-harmonic generation in AF layer. The proposed approach is generalized for the description of current-related phenomena in inhomogeneous AFMs.