Observation of the Out-of-Plane Polarized Spin Current from CVD Grown WTe2

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, centimeter-scale chemical vapor deposition (CVD) grown Td-WTe2 thin films are used and the spin current generation is studied by the spin torque ferromagnetic resonance (ST-FMR) technique. The in-plane and out-of-plane spin conductivities of 7.36 x 10(3) (PLANCK CONSTANT OVER TWO PI/2e) (ohm m)(-1) and 1.76 x 10(3) (PLANCK CONSTANT OVER TWO PI/2e) (ohm m)(-1), respectively, are found in CVD-growth 5 nm-WTe2. The current-induced magnetization switching in WTe2/NiFe is demonstrated at room temperature in the domain wall motion regime, which may invigorate potential spintronic device innovations based on Weyl semimetals.