Acoustic spin pumping; Direct generation of spin currents from sound waves in Pt/YFeO hybrid structures

Uchida, Kenichi*; Adachi, Hiroto; An, Toshu*; Nakayama, Hiroyasu*; Toda, Masaya*; Hillebrands, B.*; Maekawa, Sadamichi; Saito, Eiji

Using a Pt/YFeO (YIG) hybrid structure attached to a piezoelectric actuator, we demonstrate the generation of spin currents from sound waves. This "acoustic spin pumping" is caused by the sound wave generated by the piezoelectric actuator, which then modulates the distribution function of magnons in the YIG layer and results in a pure-spin-current injection into the Pt layer across the Pt/YIG interface. In the Pt layer, this injected spin current is converted into an electric voltage due to the inverse spin-Hall effect. The ISHE induced by the acoustic spin pumping is detected by measuring a voltage in the Pt layer at the piezoelectric resonance frequency of the actuator coupled with the Pt/YIG system. Our model calculation based on the linear response theory provides us with a qualitative and quantitative understanding of the acoustic spin pumping in the Pt/YIG system.