Oscillation of the magnetic moment in modulated martensites in Ni_2MnGa studied by ab initio calculations

摘要

We have revealed the oscillations in the distribution of the magnetic moments in modulated martensites in Ni_2MnGa ferromagnetic shape memory alloy, by first-principles density-functional calculations. It is demonstrated that the oscillation of Ni magnetic moment that depends on the atomic shuffling in the superstructure dominates the distribution of the total magnetic moment per Ni_2MnGa unit. The structure change-associated total magnetic moment has been found to increase for Ni_2MnGa unit from the cubic austenite to the tetragonal nonmodulated (NM) martensite through the monoclinic modulated martensites.