Low-temperature fabrication, magnetoresistance and spin pumping studies of polycrystalline few-layer 1T'-MoTe2 films

Two-dimensional transition metal dichalcogenides (TMDs), with their strong spin-orbit coupling, are promising candidates for spintronic memory devices. We fabricated large-area, high-quality polycrystalline few-layer 1T'MoTe2 films with tunable thickness using chemical vapor deposition at 500 degrees C. X-ray diffraction, X-ray reflectivity, scanning electron microscopy, and atomic force microscopy confirmed that the films exhibit uniform, continuous growth with well-ordered stacking along the c-axis direction. It is found that the magnetoresistance (MR) is quadratically related to the applied magnetic field when varying the temperature or magnetic field. When an out-of-plane magnetic field is applied perpendicular to the current direction, the MR is larger due to the anisotropic scattering of charge carriers in 1T'-MoTe2 with strong spin-orbit coupling, compared to the parallel direction. Spin dynamics study on the 1T'-MoTe2/NiFe/MgO/Ta heterostructure found that the perpendicular spin diffusion length of 1T'-MoTe2 is approximately 13 nm, considering the impact of spin backflow on the spin dynamics of 1T'-MoTe2/NiFe. The spin mixing conductance, spin current density, and spin Hall angle in 1T'MoTe2/NiFe/MgO/Ta are significantly higher than in typical two-dimensional TMDs-ferromagnet bilayers and comparable to metal-ferromagnet heterostructures. Thus, the extended spin diffusion length and elevated spin Hall angle in 1T'-MoTe2 offer significant benefits for spintronic device applications.