Ferromagnetic shape memory alloys: Scientific and applied aspects

The underlying mechanisms responsible for the giant magnetic or mechanical field-induced-strains in ferromagnetic shape memory alloys are briefly discussed based on a phenomenological approach. The fundamental aspect is illustrated by the experimental results related to the lattice, mechanical and magnetic instabilities in the prototype Ni–Mn–Ga materials. A strong linear dependence of the magnetization upon the twinning deformation of martensite is considered for the sensor applications. An actuation capability on the microscale is found in the Ni–Mn–Ga/substrate thin film composites.