# Spin currents and torques in ferromagnetic systems with strong interfacial spin-orbit coupling

## TL;DR

This paper explores how spin currents and torques behave in magnetic systems with strong spin-orbit coupling, offering insights for improving spintronic devices.

## Contribution

The study provides a 3D model of spin transport and reproduces angular dependencies of torques in specific magnetic systems.

## Key findings

- The angular dependence of spin-orbit torques in Pt/Co and Ta/CoFeB systems is accurately modeled.
- The Rashba-Edelstein effect generates a strong field-like torque with unconventional angular behavior.
- Spin currents produce all three spin-polarization components, enabling potential field-free switching in spintronic devices.

## Abstract

A three-dimensional description of spin-dependent current transport across nonmagnetic/ferromagnetic interfaces with strong interfacial spin-orbit coupling is presented. The resulting current-induced torques acting on the magnetization of the ferromagnetic layer are addressed. By considering both magnetic exchange and Rashba spin-orbit interactions at the interface, the angular dependence of the spin-orbit torques in Pt/Co and Ta/CoFeB systems is reproduced. In line with two-dimensional Rashba models, the Rashba-Edelstein effect drives the strong field-like torque, with the unconventional angular dependence being most pronounced, when magnetic exchange and spin-orbit interaction strengths are comparable. Furthermore, the spin currents generated through spin-orbit precession and filtering are shown to produce all three spin-polarization components, depending on the magnetization direction. Utilizing these mechanisms in current-in-plane trilayers could potentially enable field-free perpendicular and type-x switching, which is crucial for advancing the miniaturization of spintronic devices.