Thermal Generation of Spin Current in an Antiferromagnet

Abstract

The longitudinal spin Seebeck effect has been investigated for a uniaxial antiferromagnetic insulator ${\mathrm{Cr}}_2{\mathrm{O}}_3$, characterized by a spin-flop transition under magnetic field along the $c$ axis. We have found that a temperature gradient applied normal to the ${\mathrm{Cr}}_2{\mathrm{O}}_3/\mathrm{Pt}$ interface induces inverse spin Hall voltage of spin-current origin in Pt, whose magnitude turns out to be always proportional to magnetization in ${\mathrm{Cr}}_2{\mathrm{O}}_3$. The possible contribution of the anomalous Nernst effect is confirmed to be negligibly small. The above results establish that an antiferromagnetic spin wave can be an effective carrier of spin current.