We theoretically study the intrinsic thermal Hall and spin Nernst effect in collinear ferrimagnets on a honeycomb lattice with broken inversion symmetry. The broken inversion

symmetry allows in-plane Dzyaloshinskii−Moriya interaction between the nearest neighbors, which does not affect the linear spin wave theory. However, the Dzyaloshinskii−Moriya interaction induces large Berry curvature in the magnetoelastic excitations through the magnon−phonon interaction (MPI) to produce thermal Hall current. Furthermore, the magnetoelastic excitations transport spin, which is inherited from the magnons. Therefore, spin Nernst current accompanies the thermal Hall current. Because the MPI does not conserve the spin, we examine the spatial distribution of spin induced by a thermal gradient in the system having a stripe geometry. We find that spin is accumulated at the edges, reflecting the spin Nernst current. We also find that the total spin of the system and, therefore, the magnetization is changed, because of the thermal gradient and MPI.

Authors: Sungjoon Park (서울대, IBS CCES), Naoto Nagaosa, Bohm-Jung Yang^* (서울대, IBS CCES)

Publication date: 26 February 2020

https://pubs.acs.org/doi/full/10.1021/acs.nanolett.0c00363