Gigantic enhancement of spin Seebeck effect by phonon drag

スピンゼーベック効果のフォノンドラッグによる巨大な増幅

安立 裕人; 内田 健一*; 齊藤 英治; 大江 純一郎; 高橋 三郎; 前川 禎通

Adachi, Hiroto; Uchida, Kenichi*; Saito, Eiji; Oe, Junichiro; Takahashi, Saburo; Maekawa, Sadamichi

We investigate both theoretically and experimentally a gigantic enhancement of the spin Seebeck effect in a prototypical magnet LaYFeO at low temperatures. Our theoretical analysis sheds light on the important role of phonons; the spin Seebeck effect is enormously enhanced by nonequilibrium phonons that drag the low-lying spin excitations. We further argue that this scenario gives a clue to understand the observation of the spin Seebeck effect that is unaccompanied by a global spin current, and predict that the substrate condition affects the observed signal.