Irreversible magnetic-field dependence of ferromagnetic resonance and inverse spin Hall effect voltage in CoFeB/Pt bilayer

Abstract

Magnetic field (H) sweeping direction dependences of the mixed voltage Vmix induced by the inverse-spin Hall effect(ISHE) and spin-rectified effect (SRE) in a CoFeB (5nm)/Pt (10nm) bilayer structure are investigated using the ferromagnetic resonance in the TE mode cavities and coplanar waveguide methods. Conventionally, the magnitude of ISHE voltage VISH (symmetric) excluding the SRE (antisymmetric component) was unavoidably separated from the fitting curve of Vmix (a sum of a symmetric and an antisymmetric part) for one direction of H-source. By studying the ratio of the two voltage parts with the bi-directional H sweeping, the optimized VISH (no SRE condition) value which also include a well-defined spin Hall angle can be obtained via the linear response relation of ISHE and SRE components.