Efficient Spin-Orbit Torque Generation in Semiconducting WTe2 with Hopping Transport

TL;DR

This paper demonstrates that amorphous WTe2 heterostructures, deposited via sputtering, exhibit efficient spin-orbit torques, low switching currents, and tunable properties, making them promising for spintronics applications.

Contribution

It introduces amorphous WTe2 as a new, sputter-deposited, semiconducting TMD with high SOT efficiency and tunability, expanding potential for industrial spintronics use.

Findings

SOT efficiency of ~0.20 in amorphous WTe2

Low critical switching current density of ~7.05×10^9 A/m^2

Electronic transport governed by hopping mechanism

Abstract

Spin-orbit torques (SOTs) from transition metal dichalcogenides systems (TMDs) in conjunction with ferromagnetic materials are recently attractive in spintronics for their versatile features. However, most of the previously studied crystalline TMDs are prepared by mechanical exfoliation, which limits their potentials for industrial applications. Here we show that amorphous WTe2 heterostructures deposited by magnetron sputtering possess a sizable damping-like SOT efficiency {\xi}_DL^WTe2 ~ 0.20 and low damping constant {\alpha} = 0.009/pm0.001. Only an extremely low critical switching current density J_c ~ 7.05\times10^9 A/m^2 is required to achieve SOT-driven magnetization switching. The SOT efficiency is further proved to depend on the W and Te relative compositions in the co-sputtered W_100-xTe_x samples, from which a sign change of {\xi}_DL^WTe2 is observed. Besides, the electronic transport in amorphous WTe2 is found to be semiconducting and is governed by a hopping mechanism. With the above advantages and rich tunability, amorphous and semiconducting WTe2 serves as a unique SOT source for future spintronics applications.