Topological Nernst effect in a three-dimensional skyrmion-lattice phase

By measuring electrical Hall, thermal Hall, and Nernst effects, we have comprehensively investigated the topological transport properties associated with the Berry phase of noncoplanar spin structure in a possible skyrmion-lattice phase of MnGe. While the topological terms in thermal and electrical Hall conductivity decrease rapidly with temperature elevation, that in the Nernst effect can be discerned up to near the magnetic transition temperature. The topological term in transverse Peltier conductivity obeys the Mott relation and changes with temperature in proportion to the three-dimensional density of the topological spin texture. This result indicates that three dimensionally ordered skyrmions are responsible for the topological transport phenomena in MnGe.