Efficient full spin\u2013orbit torque switching in a single layer of a perpendicularly magnetized single-crystalline ferromagnet

Miao Jiang,Masaaki Tanaka,Hiroki Yamasaki,Toshiki Kanaki,Shinobu Ohya,Hirokatsu Asahara,Shoichi Sato

doi:10.1038/s41467-019-10553-x

Miao Jiang, Masaaki Tanaka + Show 5 more

Open Access

https://doi.org/10.1038/s41467-019-10553-x

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Abstract

Spin–orbit torque (SOT), which is induced by an in-plane electric current via large spin-orbit coupling, enables an innovative method of manipulating the magnetization of ferromagnets by means of current injection. In conventional SOT bilayer systems, the magnetization switching efficiency strongly depends on the interface quality and the strength of the intrinsic spin Hall Effect. Here, we demonstrate highly efficient full SOT switching achieved by applying a current in a single layer of perpendicularly magnetized ferromagnetic semiconductor GaMnAs with an extremely small current density of ∼3.4 × 105 A cm−2, which is two orders of magnitude smaller than that needed in typical metal bilayer systems. This low required current density is attributed to the intrinsic bulk inversion asymmetry of GaMnAs as well as its high-quality single crystallinity and large spin polarization. Our findings will contribute to advancements in the electrical control of magnetism and its practical application in semiconductor devices.

Highlights

Spin–orbit torque (SOT), which is induced by an in-plane electric current via large spin-orbit coupling, enables an innovative method of manipulating the magnetization of ferromagnets by means of current injection
Spin–orbit torque (SOT) magnetization switching, which is induced by a spin current that is generated by a charge current, is a promising phenomenon that can be used to improve the performance of magnetoresistive random access memory devices
The sample examined in this study is composed of Ga0.94Mn0.06As (7 nm)/In0.3Ga0.7As (500 nm)/GaAs (50 nm) grown on a GaAs (001) substrate via molecular beam epitaxy (MBE)

Summary

Introduction

Spin–orbit torque (SOT), which is induced by an in-plane electric current via large spin-orbit coupling, enables an innovative method of manipulating the magnetization of ferromagnets by means of current injection. We demonstrate highly efficient full SOT switching achieved by applying a current in a single layer of perpendicularly magnetized ferromagnetic semiconductor GaMnAs with an extremely small current density of ∼3.4 × 105 A cm−2, which is two orders of magnitude smaller than that needed in typical metal bilayer systems. This low required current density is attributed to the intrinsic bulk inversion asymmetry of GaMnAs as well as its high-quality single crystallinity and large spin polarization. We show that the effective fields due to the spin–orbit interactions can induce a spin component whose direction depends on the current orientation and that this spin component can exert a damping-like torque on the magnetic moment,

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