Spin Seebeck effect in the layered ferromagnetic insulators CrSiTe${}_3$ and CrGeTe${}_3$

Abstract

We have studied the longitudinal spin Seebeck effect (LSSE) in the layered ferromagnetic insulators CrSiTe${}_3$ and CrGeTe${}_3$ covered by Pt films in the measurement configuration where spin current traverses the ferromagnetic Cr layers. The LSSE response is clearly observed in the ferromagnetic phase and, in contrast to a standard LSSE magnet Y${}_3$Fe${}_5$O${}_{12}$, persists above the critical temperatures in both CrSiTe${}_3$/Pt and CrGeTe${}_3$/Pt samples. With the help of a numerical calculation, we attribute the LSSE signals observed in the paramagnetic regime to exchange-dominated interlayer transport of in-plane paramagnetic moments reinforced by short-range ferromagnetic correlations and strong Zeeman effects.

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