Intrinsic magnon Nernst effect in pyrochlore iridate thin films
We theoretically study the magnon spin thermal transport using a strong coupling approach in py- rochlore iridate trilayer thin ﬁlms grown along the  direction. As a result of the Dzyaloshinskii- Moriya interaction (DMI), the spin conﬁguration of the ground state is an all-in/all-out ordering on neighboring tetrahedra of the pyrochlore lattice. In such a state, the system has an inversion symmetry and a Nernst-type thermal spin current response is well deﬁned. We calculate the tem- perature dependence of the magnon Nernst response with respect to the magnon band topology controlled by the spin-orbit coupling parameters and observe topologically protected chiral edge modes over a range of parameters. Our study complements prior work on the magnon thermal Hall eﬀect in thin-ﬁlm pyrochlore iridates and suggests that the  grown thin-ﬁlm pyrochlore iridates are a promising candidate for thermal spin transport and spin caloritronic devices.