Observation of the out-of-plane polarized spin current from CVD grown WTe2

TL;DR

This study demonstrates the generation of out-of-plane polarized spin currents from wafer-scale CVD-grown WTe2 thin films, showing potential for practical spintronic devices due to measurable spin conductivities and room-temperature magnetization switching.

Contribution

First demonstration of out-of-plane polarized spin current generation from wafer-scale CVD-grown WTe2 thin films with quantifiable spin conductivities and room-temperature magnetization switching.

Findings

Measured in-plane and out-of-plane spin conductivities of 7.36 x 10^3 and 1.76 x 10^3 (h/2e)(ohm-m)^-1.

Achieved current-induced magnetization switching in WTe2/NiFe at room temperature.

Demonstrated feasibility of wafer-scale WTe2 for spintronic applications.

Abstract

Weyl semimetal Td-phase WTe2 possesses the spin-resolved band structure with strong spin-orbit coupling, holding promises as a useful spin source material. The noncentrosymmetric crystalline structure of Td-WTe2 endows the generation of the out-of-plane polarized spin, which is of great interest in magnetic memory applications. Previously, WTe2 was explored in spin devices based on mechanically exfoliated single crystal flakes with a size of micrometers. For practical spintronics applications, it is highly desirable to implement wafer-scale thin films. In this work, we utilize centimeter-scale chemical vapor deposition (CVD)-grown Td-WTe2 thin films and study the spin current generation by the spin torque ferromagnetic resonance technique. We find the in-plane and out-of-plane spin conductivities of 7.36 x 10^3 (h/2e) (ohm-m)^-1 and 1.76 x 10^3 (h/2e) (ohm-m)^-1, respectively, in CVD-growth 5 nm-WTe2. We further demonstrate the current-induced magnetization switching in WTe2/NiFe at room temperature in the domain wall motion regime, which may invigorate potential spintronic device innovations based on Weyl semimetals.