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

Area of Science:

• Materials Science
• Condensed Matter Physics
• Spintronics

Background:

• Spin-orbit torques (SOTs) are crucial for spintronics, with transition metal dichalcogenide (TMD) systems showing promise.
• Current methods using crystalline TMDs via mechanical exfoliation limit industrial scalability.

Purpose of the Study:

• To investigate the SOT properties of amorphous WTe2 heterostructures prepared by magnetron sputtering.
• To explore the potential of amorphous WTe2 as a SOT source for spintronics applications.

Main Methods:

• Fabrication of amorphous WTe2 heterostructures using magnetron sputtering.
• Characterization of SOT efficiency (ξDLWTe), damping constant (α), and critical switching current density (Jc).
• Analysis of electronic transport properties and compositional dependence of SOT efficiency.

Main Results:

• Amorphous WTe2 films demonstrate a significant damping-like SOT efficiency (ξDLWTe ≈ 0.20) and a low damping constant (α = 0.009 ± 0.001).
• Extremely low critical switching current density (Jc ≈ 7.05 × 10^9 A/m^2) was achieved for SOT-driven magnetization switching.
• SOT efficiency is tunable with W and Te composition, exhibiting a sign change, and electronic transport is semiconducting via hopping.

Conclusions:

• Amorphous WTe2, prepared by sputtering, is a promising SOT material due to its high efficiency and low switching current.
• The tunable and semiconducting nature of amorphous WTe2 makes it a versatile source for future spintronics devices.