Magnetic structure of the modulated martensite phase in Ni-Mn-Ga ferromagnetic shape memory alloys

摘要

The magnetic structure of the seven layered (7M) modulated martensite phases in Mn-rich Ni-Mn-Ga alloys was studied using Mossbauer spectroscopy. The Mossbauer results clearly demonstrate that in contrast to the non-modulated tetragonal structure two new magnetic sublattices exists for the 7 M orthorhombic martensite phase. Based on the unit cell symmetry and atomic coordination, the additional magnetic sublattices have been assigned to the Ni site. The variation in the magnetic properties of the martensite phases has been related to the underlying magnetic structure.