RESUMO
Quantized spin excitations in a single ferromagnetic microstrip have been measured using the microwave photovoltage technique. Several kinds of spin wave modes due to different contributions of the dipole-dipole and the exchange interactions are observed. Among them are a series of distinct dipole-exchange spin wave modes, which allow us to determine precisely the subtle spin boundary condition. A comprehensive picture for quantized spin excitations in a ferromagnet with finite size is thereby established. The dispersions of the quantized spin wave modes have two different branches separated by the saturation magnetization.
RESUMO
We demonstrate a room-temperature spin dynamo where the precession of electron spins in ferromagnets converts energy from microwaves to a bipolar current of electricity. The current/power ratio is at least 3 orders of magnitude larger than that found previously for spin-driven currents in semiconductors. The observed bipolar nature and intriguing symmetry are fully explained by the spin rectification effect via which the nonlinear combination of spin and charge dynamics creates dc currents.
RESUMO
We investigate the impact of microwave excited spin excitations on the dc charge transport in a ferromagnetic (FM) grating. We observe both resonant and nonresonant microwave photoresistance, which are caused, respectively, by spin and charge dissipations of the microwave power into the FM. A macroscopic model based on Maxwell and Landau-Lifschitz equations reveals the mixing of spin and charge dissipations, which shows that the ferromagnetic anti-resonance is shifted when the conductivity is anisotropic. We find that the microwave photoconductivity provides a powerful new tool to study the interplay between photonic, spintronic, and charge effects in FM microstructures.
