Energy-efficient W$_{\text{100-x}}$Ta$_{\text{x}}$/CoFeB/MgO spin Hall nano-oscillators

TL;DR

This paper demonstrates that alloying tungsten with tantalum in spin Hall nano-oscillators significantly reduces the auto-oscillation current and power consumption, advancing energy-efficient spintronic device technology.

Contribution

It introduces a W-Ta alloying approach that enhances spin-orbit torque efficiency and reduces power use in nano-oscillators, a novel method for energy-efficient spintronic devices.

Findings

34% reduction in auto-oscillation current density

64% reduction in power consumption

Improved spin Hall conductivity and torque efficiency

Abstract

We investigate a W-Ta alloying route to reduce the auto-oscillation current densities and the power consumption of nano-constriction based spin Hall nano oscillators. Using spin-torque ferromagnetic resonance (ST-FMR) measurements on microbars of W$_{\text{100-x}}$Ta$_{\text{x}}$(5 nm)/CoFeB(t)/MgO stacks with t = 1.4, 1.8, and 2.0 nm, we measure a substantial improvement in both the spin-orbit torque efficiency and the spin Hall conductivity. We demonstrate a 34\% reduction in threshold auto-oscillation current density, which translates into a 64\% reduction in power consumption as compared to pure W-based SHNOs. Our work demonstrates the promising aspects of W-Ta alloying for the energy-efficient operation of emerging spintronic devices.