High Spin-Charge Conversion Efficiency of Co3Sn2S2 Promoted by Transition from Paramagnetic to Ferromagnetic Phase

Temperature (T) dependence of conversion from charge current to spin current was investigated for the Co3Sn
2
S
2
(CSS) thin film by measuring the spin-torque ferromagnetic resonance (ST-FMR) for the sample with CSS / Cu / CoFeB. Above the ferromagnetic phase transition temperature (T
C
), the sample exhibited the clear ST-FMR signal coming from the spin Hall effect in the paramagnetic CSS and the anisotropic magnetoresistance (AMR) of CoFeB. Below T
C
, on the other hand, it is found that the ST-FMR signal involves the dc voltages not only through the AMR but also through the giant magnetoresistance. In addition, the spin Hall torque generated from the ferromagnetic CSS dominantly acts on the CoFeB magnetization. An increase in the spin-charge conversion efficiency is observed at T < T
C
, indicating that the phase transition from the paramagnetic CSS to the ferromagnetic CSS promotes the spin-charge conversion.