![]() We thereby measure the electric power transfer from the spin-pumping device into the external load resistor, which was not much discussed previously. In this scheme, instead of using an open circuit, we close the circuit with a load resistor, which allows us to measure the generated charge current in a spin-pumping device using the ISHE. In this paper, we introduce a charge current detection method for spin pumping in a macroscopic closed circuit. (d) MW excitation power dependence of the voltage peak height Δ V open (dot) with a linear fit line (solid curve). The measurement MW frequency was 4 GHz, and the magnetic field was applied perpendicular to the voltage measurement direction in-plane. The results for both the positive (solid lines) and negative (dashed lines) magnetic-field directions are shown, for comparison. (c) Voltage ( V open) measured across the sample for different powers. (b) FMR spectra measured at a frequency of 4 GHz and 20-mW MW power using AC-modulation techniques. 1. (a) Schematic of spin-pumping and the ISHE mechanism in an FM and NM bilayer sample. Although this is an electric charge–current excitation picture, the commonly used circuitry for spin-pumping measurements is based on an open circuit, where the electric voltages are measured and discussed as a signature of spin pumping and the ISHE.įig. High-spin orbit materials such as Pt are often used as good SHE materials for the efficient detection of the spin currents. The spin currents are then converted into charge currents through the ISHE, as illustrated in Fig. One of the dissipation mechanisms in a FM/non-magnetic (NM) bilayer involves the transfer of angular momentum to electron spins in the NM layer, where spin currents are generated. 9 ) When the magnetic dynamics are driven by microwave (MW) absorption of a ferromagnetic (FM) material, non-equilibrium spin waves are accumulated and dissipated at a fixed rate. 6 – 8 ) Another widely used method for generating spin currents is spin-pumping using magnetic dynamics. 4 ) Through the inverse spin Hall effect (ISHE), 5 ) charge currents can be converted into a spin current that flows perpendicular to the charge flow orientation, and a wide range of thin-film metallic and semiconducting materials have been examined for the efficient generation and detection of spin currents through the SHE. 3 ) The generation of spin currents has been widely explored in the last decade. For example, they can be used to manipulate magnetic dynamics, 1 ) switch magnetic moments, 2 ) and facilitate spintronic energy-harvesting applications. Spin currents, i.e., the flow of angular momentum without the simultaneous transfer of electrical charge, play a pivotal role in the current developments of spintronic research.
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