Strain and concurrent magnetization changes in magnetic shape memory Ni–Mn–Ga single crystals – experiment and model

The magnetic shape memory phenomenon represents two effects—the magnetic-field-induced strain and the magnetic-field-assisted superelasticity. These are accompanied by large magnetization changes due to anisotropic magnetic properties of the martensite twin variants. Simultaneous measurements of strain and overall magnetization using vibrating coil magnetometer provide the correlation between the ratio of martensitic variants and magnetization changes. A simple model, using known parameters of martensite structure and magnetic behavior of martensite variants with different orientations, is used to describe the observed behavior. From the model we predict the magnetization and strain changes for arbitrary combinations of the magnetic field and mechanical loading. The calculated dependencies agree well with the experiment.