Origin of the spin Seebeck effect in compensated ferrimagnets

磁気補償されたフェリ磁性体におけるスピンゼーベック効果の起源

Geprgs, S.*; Kehlberger, A.*; Coletta, F.*; Qiu, Z.*; Guo, E.-J.*; Schulz, T.*; Mix, C.*; Meyer, S.*; Kamra, A.*; Althammer, M.*; Huebl, H.*; Jakob, G.*; 大沼 悠一*; 安立 裕人; Barker, J.*; 前川 禎通; Bauer, G. E. W.*; 齊藤 英治; Gross, R.*; Goennenwein, S. T. B.*; Klui, M.*

Geprgs, S.*; Kehlberger, A.*; Coletta, F.*; Qiu, Z.*; Guo, E.-J.*; Schulz, T.*; Mix, C.*; Meyer, S.*; Kamra, A.*; Althammer, M.*; Huebl, H.*; Jakob, G.*; Onuma, Yuichi*; Adachi, Hiroto; Barker, J.*; Maekawa, Sadamichi; Bauer, G. E. W.*; Saito, Eiji; Gross, R.*; Goennenwein, S. T. B.*; Klui, M.*

Magnons are the elementary excitations of a magnetically ordered system. Here, we show that the spin Seebeck effect is sensitive to the complexities of the magnon spectrum. The spin Seebeck effect is caused by a thermally excited spin dynamics that is converted to a voltage by the inverse spin Hall effect at the interface to a heavy metal contact. By investigating the temperature dependence of the spin Seebeck effect in the ferrimagnet gadlinium iron garnet, with a magnetic compensation point near room temperature, we demonstrate that high-energy exchange magnons play a key role in the spin Seebeck effect.