Efficient magnetization switching driven by orbital torque originating from light 3d-transition-metal nitrides

TL;DR

This paper demonstrates efficient perpendicular magnetization switching driven by orbital torque from light 3d transition-metal nitrides, specifically VN, offering a promising alternative to heavy metal-based spintronic devices.

Contribution

It introduces the use of light 3d transition-metal nitrides like VN to generate orbital torques for magnetization switching, surpassing traditional heavy metal approaches.

Findings

Large torque efficiency of -0.41 in VN-based multilayers

Successful full magnetization switching with in-plane current and magnetic field

First-principles calculations show high orbital Hall conductivity in VN

Abstract

The orbital Hall effect (OHE) in light transition metals offers a promising route to generate orbital torques for efficient magnetization control, providing an alternative to conventional spin Hall effect approaches that rely on heavy metals. We demonstrate perpendicular magnetization switching in [Co/Pt]3 multilayers driven by the OHE in a light 3d transition metal nitride, VN, with 111-texture of face-center cubic structure. Second harmonic Hall measurement reveals a large torque efficiency of -0.41 in the VN(7.5 nm)/[Co(0.35nm)/Pt(0.3 nm)]3, which significantly surpasses that in the control samples with Co, Py, and CoFeB ferromagnets, suggesting strong conversion of orbital current originating from VN to spin current by [Co/Pt]3 ferromagnet. Full switching by in-plane current is achieved with an in-plane magnetic field, while partial field-free switching occurs without it. The critical current density for the switching is found to be comparable to that of the W-based spin-orbit torque device. First-principles calculations confirm a large orbital Hall conductivity in VN, with a small spin Hall conductivity around the Fermi energy. Our results highlight the potential in the combination of light 3d transition metal nitrides and Co/Pt ferromagnetic multilayer with 111-texture to maximize the magnetization switching efficiency of orbitronic devices.