Large Magneto-thermopower in MnGe with topological spin texture

A topological spin texture—a three-dimensional array of hedgehogs and anti-hedgehogs—shows up in a chiral magnet MnGe. Those hedgehog-type spin textures serve as “emergent” magnetic monopoles whose fluctuations critically affect charge transport phenomena.
We report an unusual magneto-thermopower which exhibits a strong enhancement towards the topological phase transition (hedgehog lattice to ferromagnetic state) with applying magnetic field. By considering all conceivable origins through quantitative investigations on electronic structures and properties, a possible origin of the observed effect is assigned to unconventional scattering mechanism arising from the dynamics of emergent magnetic field. The proposed mechanism is also corroborated by high field measurements of Seebeck effect and magneto-resistivity, which revealed the far-reaching effect of surviving magnetic fluctuations even in the ferromagnetic region.
Our finding will not only illustrate the unique topological phenomena rooted in the dense lattice of singular defects like hedgehogs, but may also motivate the search of thermoelectric functions in topological magnets.