Synthesis and Characterization of Ni-Mn-X (X: In, Sb) FSMA Thin Films

In recent years, Ni-Mn-X (X: In, Sb) based ferromagnetic shape memory alloys (FSMAs) showing a reversible first-order martensitic phase transformation between high symmetry austenitic phase to low symmetry martensitic phase accompanied with a macroscopic shape change, have attracted increasing scientific attention as multifunctional materials due to their large magnetic-field-induced strains (MFIS) by the rearrangement of twin variants in the martensite and as potential candidates for high sensitivity magnetic actuators and sensors. These alloys exhibit various magnetic field-driven properties such as magnetic shape memory effect, martensitic phase transformation, exchange bias effect and magnetocaloric effect etc. So far, numerous groups have studied these magnetic field-driven properties in bulk FSMAs. For emerging micro devices such as magnetically driven microelectromechanical systems (MEMS) and even microscopic machines, high quality FSMA thin films grown on semiconductor substrates are required. It is desirable to establish the process for producing high quality thin films of these materials for their integration into emerging technologies. 

The main objective of the present work was to synthesize nanostructured ferromagnetic shape memory alloy thin films of Ni-Mn-X (X: In, Sb) on Si (100) substrate using DC magnetron sputtering technique to investigate the structural, phase transformation, magneticand mechanical properties of these films. In addition Ni-Mn-Sb/CrN heterostructures were fabricated and the effect of varying thickness of CrN layer on various properties of heterstructure was studied.