# Spin-transfer torques for domain walls in antiferromagnetically coupled ferrimagnets

## TL;DR

This paper presents experimental evidence that spin-transfer torque can effectively drive domain walls in antiferromagnetically-coupled ferrimagnets, revealing a larger non-adiabaticity parameter than damping, which enables faster antiferromagnetic device operation.

## Contribution

It provides the first experimental demonstration of STT effects on domain walls in antiferromagnetically-coupled ferrimagnets, challenging existing ferromagnetic-based models.

## Key findings

- Non-adiabatic STT acts like a staggered magnetic field.
- The non-adiabaticity parameter {eta} exceeds the Gilbert damping {\u03b1}.
- Fast current-induced domain wall motion observed.

## Abstract

Antiferromagnetic materials are outstanding candidates for next generation spintronic applications, because their ultrafast spin dynamics makes it possible to realize several orders of magnitude higher-speed devices than conventional ferromagnetic materials1. Though spin-transfer torque (STT) is a key for electrical control of spins as successfully demonstrated in ferromagnetic spintronics, experimental understanding of STT in antiferromagnets has been still lacking despite a number of pertinent theoretical studies2-5. Here, we report experimental results on the effects of STT on domain-wall (DW) motion in antiferromagnetically-coupled ferrimagnets. We find that non-adiabatic STT acts like a staggered magnetic field and thus can drive DWs effectively. Moreover, the non-adiabaticity parameter {\beta} of STT is found to be significantly larger than the Gilbert damping parameter {\alpha}, challenging our conventional understanding of the non-adiabatic STT based on ferromagnets as well as leading to fast current-induced antiferromagnetic DW motion. Our study will lead to further vigorous exploration of STT for antiferromagnetic spin textures for fundamental physics on spin-charge interaction as wells for efficient electrical control of antiferromagnetic devices.

---
Source: https://tomesphere.com/paper/1903.03251