Measurement of spin current using spin relaxation modulation induced by spin injection

Ferromagnetic resonance spectra affected by the spin-Hall effect (SHE) and the spin torque were measured for a Ni(81)Fe(19)/Pd bilayer film. A charge current applied to the Pd layer is converted into a spin current via SHE, which propagates into the Ni(81)Fe(19) layer through the interface as a spin current. The spin current exerts the torque on the magnetization, modulating the spin relaxation in the Ni(81)Fe(19) layer. By monitoring the spin relaxation modulation, we estimated the spin current amplitude injected into the Ni(81)Fe(19) layer. This method enables the quantitative measurement of spin currents without assuming any microscopic material parameters. (C) 2009 American Institute of Physics. [DOI: 10.1063/1.3063081]