Large topological Hall effect in nonchiral hexagonal MnNiGa films

Abstract

We report a systematic study of the magnetic and transport properties of magnetron sputtered nonchiral hexagonal MnNiGa films on the thermally oxidized Si substrates as a function of film thickness. A large topological Hall effect (THE) is observed, and its magnitude increases correspondingly with increasing the film thickness. The large THE appears in a very wide temperature range of 10 K–300 K in a magnetic field region where the field-dependent Hall resistivity largely deviates from the magnetization. Moreover, the measurements on the cubic MnNiGa films do not show any evidence of the existence of THE. These results indicate that the non-collinear spin configurations from geometrical frustration of Mn moments are the likely origin of the observed large THE in hexagonal MnNiGa films.