Long-range spin Seebeck effect and acoustic spin pumping

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

We show that, using a NiFe/Pt bilayer wire on an insulating sapphire plate, electrons in the wire recognize their position on the sapphire. Under a temperature gradient in the sapphire, surprisingly, the voltage generated in the Pt layer is shown to reflect the wire position, although the wire is isolated both electrically and magnetically. This non-local voltage due to the coupling of spins and phonons: the only possible carrier of information in this system. We demonstrate this coupling by directly injecting sound waves, which realizes the acoustic spin pumping. Our finding provides a persuasive answer to the long-range nature of the spin Seebeck effect, and it opens the door to "acoustic spintronics" in which sound waves are exploited for constructing spin-based devices.