New Aspects of Structural and Magnetic Behaviour of Martensites in Ni-Mn-Ga Alloys

Abstract

The structural changes and magnetic anomalies accompanying martensitic transformations in Ni–Mn–Ga alloys are briefly discussed. The role of lattice tetragonality of martensite in the reduction of magnetic field needed for the observation of large magnetostrain effect is theoretically analyzed, considering the compensation of the magnetic anisotropy. The possibility of the field reduction is based on the previously observed lattice parameter dependence on the temperature and proper fit of the alloy specimen shape. The model shows that a significant reduction of the magnetic field needed for the giant MSE can take place in martensites with 0.98<c⁄a<1.04.