Planar Hall driven torque in a FM/NM/FM system

TL;DR

This paper demonstrates that the planar Hall effect in a CoNi multilayer can generate spin currents capable of exerting torques on an adjacent magnetic layer, offering a new method for spin current generation in spintronics.

Contribution

It introduces the use of planar Hall effect in a ferromagnetic system as a controllable spin current source, comparable to the spin Hall effect in platinum.

Findings

Planar Hall effect produces measurable spin torques in FM/NM/FM systems.

The torque strength is comparable to the spin Hall effect in platinum.

The effect's symmetry aligns with theoretical expectations for planar Hall-induced torques.

Abstract

An important goal of spintronics is to covert a charge current into a spin current with a controlled spin polarization that can exert torques on an adjacent magnetic layer. Here we demonstrate such torques in a two ferromagnet system. A CoNi multilayer is used as a spin current source in a sample with structure CoNi/Au/CoFeB. Spin torque ferromagnetic resonance is used to measure the torque on the CoFeB layer. The response as a function of the applied field angle and current is consistent with the symmetry expected for a torques produced by the planar Hall effect originating in CoNi. We find the strength of this effect to be comparable to that of the spin Hall effect in platinum, indicating that the planar Hall effect holds potential as a spin current source with a controllable polarization direction.