Enhancing spin-orbit torque by strong interfacial scattering from ultra-thin insertion layers

TL;DR

This paper demonstrates that inserting ultra-thin layers within spin Hall metals can significantly enhance dampinglike spin-orbit torque, leading to lower power consumption in spintronic devices.

Contribution

The study introduces a novel method of increasing spin-orbit torque by enhancing interfacial scattering with ultra-thin insertion layers, achieving record low switching currents.

Findings

Dampinglike SOT was doubled with sub-monolayer Hf insertion.

Record low switching current of ~73 μA was achieved.

Enhanced interfacial scattering improves spin Hall ratio.

Abstract

Increasing dampinglike spin-orbit torque (SOT) is both of fundamental importance for enabling new research into spintronics phenomena and also technologically urgent for advancing low-power spin-torque memory, logic, and oscillator devices. Here, we demonstrate that enhancing interfacial scattering by inserting ultra-thin layers within a spin Hall metals with intrinsic or side-jump mechanisms can significantly enhance the spin Hall ratio. The dampinglike SOT was enhanced by a factor of 2 via sub-monolayer Hf insertion, as evidenced by both harmonic response measurements and current-induced switching of in-plane magnetized magnetic memory devices with the record low critical switching current of ~73 uA (switching current density of 3.6x10^6 A/cm^2). This work demonstrates a very effective strategy for maximizing dampinglike SOT for low-power spin-torque devices.