Md. Majibul Haque Babu (The University of Texas at Austin)

"Spin rectification effects in ferromagnetic resonance"

Abstract: Spin rectification effects are widely used to study magnetization dynamics in magnetic materials and spintronic devices. For instance, ferromagnetic resonance (FMR) can be easily detected by measuring a dc photovoltage resulting from the rectification of rf current in a ferromagnet with oscillating magnetization. Here we present an experimental study of the rectification effects produced by FMR in a ferromagnetic (NiFe) wire. First, we study the dependence of FMR on the relative orientation (angle θ) between the driving rf current and the static magnetic field. We find a simple “1/"cos" (θ)" dependence for the resonance field which emphasizes the importance of the driving current direction in FMR experiments. Second, we used a system of four independent nonmagnetic contacts to supply both rf and dc currents to the ferromagnetic wire and measure the resulting photovoltage at different locations in the wire. The system provides a means to separate contributions to spin rectification from the ferromagnet/nonmagnet contacts and the ferromagnet’s bulk and highlights the importance of contact properties for rectification effects in spintronic devices.