Gigantic enhancement of spin Seebeck effect by phonon drag

Hiroto Adachi, Ken-ichi Uchida, Eiji Saitoh, Jun-ichiro Ohe, Saburo Takahashi, Sadamichi Maekawa

Published 2010-10-22, updated 2011-01-31Version 2

We investigate both theoretically and experimentally a gigantic enhancement of the spin Seebeck effect in a prototypical magnet LaY$_2$Fe$_5$O$_{12}$ 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.