Gate voltage tuning of spin current in Pt/yttrium iron garnet heterostructure

Electric gating provides a versatile tool to create new spintronic materials and functionalities. Here, we have shown significant tuning effects of the gate voltage via ionic liquid on spin pumping and spin Hall magnetoresistance in Pt/yttrium iron garnet heterostructure. It is found that the interfacial spin mixing conductance is greatly enhanced upon application of the gate voltage. In addition, and interestingly, the spin relaxation time also increases with the gate voltage. Moreover, suppressed spin Hall magnetoresistance and enhanced spin polarization of Pt atoms both suggest that the spin Hall angle is reduced by the gate voltage. All these results can be consistently explained by the enhanced charge carrier density and the subsequent elevated Fermi level induce by the gate voltage. By tackling the key parameters in controlling the generation and propagation of pure spin current via voltage gating, the present work provides novel strategies to improve the performance of the spin current devices. (paper)