Antisite disorder induced spin glass and exchange bias effect in Nd_2NiMn0_6 epitaxial thin film

摘要

We report the observation of the exchange bias effect and spin glass behaviour at low temperature in a ferromagnetic Nd_2NiMn0_6 epitaxial thin film. Along with the ferromagnetic transition at~194 K, an additional transition is observed at lower temperature (~55 K) as seen from M-T curves of the sample. A shift in the ac susceptibility peak with frequency has been observed at low temperature, which is a signature of a glassy phase within the sample. The detailed investigation of the memory effect and time dependent magnetic relaxation measurements reveals the presence of a spin glass phase in the Nd_2NiMn0_6 thin film. The exchange bias effect observed at low temperature in the sample has been associated with an antisite disorder induced spin glass phase, which results in a ferromagnetic/spin glass interface at low temperature. The exchange bias behaviour has been further confirmed by performing cooling field and temperature dependence of exchange bias along with training effect measurements.