Magnon-drag thermoelectric transport with skyrmion structure

Abstract

Thermoelectric effects driven by magnetization dynamics under a temperature gradient are studied for ferromagnets with and without a skyrmion structure. We calculate charge currents in a four-terminal geometry using the adiabatic pumping formula with full account of magnetization dynamics based on the stochastic Landau-Lifshitz-Gilbert equation. The longitudinal current (Seebeck effect) is induced from the thermally driven spin waves via the spin-transfer and momentum-transfer processes, and these two processes contribute constructively (destructively) in ferromagnets having a negative (positive) s-d exchange interaction. The transverse currents (anomalous Nernst effect) arise in proportion to the number of skyrmions, whose mechanism is identified as the thermal topological Hall effect of magnons followed by the momentum-transfer drag process.