Spin-polarized current effect on antiferromagnet magnetization in a ferromagnet - antiferromagnet nanojunction: Theory and simulation

TL;DR

This paper investigates how spin-polarized currents influence the magnetization of antiferromagnets in nanojunctions, combining theoretical analysis and simulations to reveal low-damping terahertz oscillations and instability phenomena.

Contribution

It generalizes the macrospin approximation to antiferromagnets and analyzes the effects of spin-polarized currents on magnetization dynamics in a ferromagnet-antiferromagnet nanojunction.

Findings

Resonance frequency and damping are calculated.

Low-damping magnetization oscillations in terahertz range are possible.

Numerical simulations agree with analytical linear approximation outside instability range.

Abstract

Spin-polarized current effect is studied on the static and dynamic magnetization of the antiferromagnet in a ferromagnet - antiferromagnet nanojunction. The macrospin approximation is generalized to antiferromagnets. Canted antiferromagnetic configuration and resulting magnetic moment are induced by an external magnetic field. The resonance frequency and damping are calculated, as well as the threshold current density corresponding to instability appearance. A possibility is shown of generating low-damping magnetization oscillations in terahertz range. The fluctuation effect is discussed on the canted antiferromagnetic configuration. Numerical simulation is carried out of the magnetization dynamics of the antiferromagnetic layer in the nanojunction with spin-polarized current. Outside the instability range, the simulation results coincide completely with analytical calculations using linear approximation. In the instability range, undamped oscillations occur of the longitudinal and transverse magnetization components.