Giant Damping-like Torque Efficiency via Synergistic Spin Hall and enhanced Orbital Hall Effects

TL;DR

This paper demonstrates a significant enhancement in spin-orbit torque efficiency by combining improved crystallographic texture with synergistic spin and orbital Hall effects, advancing energy-efficient spintronic device performance.

Contribution

It introduces a novel approach of interface engineering and crystallinity control to leverage both spin and orbital Hall effects for higher torque efficiency.

Findings

Switching efficiency increased by over 44%

Crystallographic texture improvement enhances orbital Hall effect

Synergistic use of spin and orbital DoFs boosts performance

Abstract

Current-induced spin-orbit torque (SOT) has emerged as a promising method for achieving energy-efficient magnetisation switching in advanced spintronic devices. Over the past two decades, researchers have primarily focused on enhancing spin current generation through the spin Hall effect, relying predominantly on the spin degree of freedom (DoF) of the electron, while neglecting its orbital counterpart. Orbital Hall effect depends critically on the crystallinity and the interface between the orbital Hall layer and the orbital-to-spin conversion layer. However, most experimental works on orbital Hall effect relied on polycrystalline films with no special attention to improve the crystallographic texture. In this work, we have grown the Ru layer on a NiW seedlayer, which helped to improve the crystallographic texture, thereby enhancing the switching efficiency by over 44%. Such a huge increase in switching efficiency was achieved by (i) improving crystallographic texture and (ii) leveraging both spin and orbital DoFs. Our study underscores the potential for improving the spin-torque efficiency by combining interface engineering, orbital and spin Hall effects to drive next-generation spintronics.