Investigation of Transition Metal-doped Zinc Oxide for Spintronics

Transition metal-doped zinc oxide (ZnTMO) grown using metal-organic chemical vapor deposition exhibited spin-related properties at room temperature that are driven by secondary phases, defects, transition metal clusters, and extrinsic carrier scattering. ZnTMO has been an interesting material for spintronics and has shown ferromagnetism at room temperature in the literature. However, the mechanism for spin-characteristics is not clear. In this work, Anomalous Hall Effect measurements were performed to investigate these mechanisms. A non-linear trend of transverse Hall resistvity with externally applied field indicated spin polarization in the material. However, variations in transverse resistivity with applied magnetic field follow same trend as four-point Van der Pauw resistivity. Hence, the Anomalous Hall Effect is likely not due to intrinsic free carriers. Spin-related properties of ZnTMO are dominantly influenced by secondary phases, native defects, and other extrinsic carrier-scattering centers such as transition metal clusters. This work contributes towards the understanding of ZnTMO for spintronic applications and provides better clarity regarding the underlying phenomena for its spin-related properties.