Phase structure and magnetic properties of the annealed Mn-rich Ni–Mn–Ga ferromagnetic shape memory thin films.

The phase structure and magnetic behavior of sputter deposited and annealed Ni–Mn–Ga thin films of varying thickness have been studied. The as-deposited films exhibited quasi-amorphous structure having paramagnetic nature at room temperature. After annealing at 873 K for 30 min ferromagnetic ordering is recovered and the quasi-amorphous structure has changed to nanocrystalline structure. At low film thickness (<300 nm), the annealed films exhibited a mixture of cubic austenite (L2 1 ) and martensite phases while at thickness greater than 1000 nm ordered L1 2 phase was observed. The magnetic properties were found to strongly depend on the structure of the constituent phases in the films. [ABSTRACT FROM AUTHOR]