# Sub-terahertz ferrimagnetic spin-transfer torque oscillator

## TL;DR

This paper develops a theoretical model for magnetization dynamics in ferrimagnetic GdFeCo layers under spin-transfer torque, revealing potential for sub-terahertz frequency precession and magnetization switching.

## Contribution

It introduces a new theory describing ferrimagnetic magnetization dynamics under STT, highlighting conditions for high-frequency precession and switching regimes.

## Key findings

- Precession frequency can reach sub-THz levels.
- Conical precession depends on STT strength and spin non-compensation.
- Two regimes: deterministic switching and conical precession.

## Abstract

A theory of magnetization dynamics in ferrimagnetic materials with antiparallel aligned spin sub-lattices under action of spin-transfer torques (STT) is developed. We consider magnetization dynamics in GdFeCo layers in two cases of magnetic anisotropy: easy plane and easy axis. We demonstrate that, (i) for the easy plane anisotropy the precession of the N\'{e}el vector is conical and the cone angle depends on the STT strength and the value of spin non-compensation, while the frequency of precession can reach sub-THz frequencies; (ii) for the easy axis anisotropy two regimes are possible: deterministic switching of the net magnetization and a conical sub-THz precession depending on the STT strength.