Study On Preparation Technology And Mechanism Of Phase Transformation And Magnetic Property Of Free-standing Ni-Mn-In Alloy Thin Films

Free-standing Ni-Mn-In magnetic shape memory thin films have been deposited on photoresist film substrate by the method of magnetron sputtering technique.Comparing the films deposited on different substrates by several separation methods,the method for obtaining free-standing Ni-Mn-In alloy thin film has been determined.Furthermore,the effect of preparation parameters on composition,surface morphology and crystallization behavior of Ni-Mn-In thin film has been investigated by means of EDS,AFM and DSC.Moreover,the mechanism of effect of Co doping on martensitic transformation and magnetic properties has been revealed based on the electronic structure.Several methods for preparing free-standing Ni-Mn-In alloy thin film have been studied in detail.It is found that the high quality free-standing Ni-Mn-In alloy thin film can be obtained by depositing film on the photoresist and separating the film from substrate by acetone.The research results indicate that the sputtering parameters have significant effect on surface morphology of free-standing Ni-Mn-In films.The surface roughness of thin film increases with increasing sputtering power.The sputtering time has little effect on surface roughness.The sputtering power has nearly no influence on the content of Ni Mn and In.The chemical composition remains unchanged under variation of sputtering time.The crystallization behavior of Ni-Mn-In thin film has been revealed for the first time based on the preparation of free-standing films.It is found that the crystallization temperature of Ni-Mn-In thin film is approximately 400 °C.The peak of the crystallization curve shifts toward the higher temperature when the heating rate increases.The crystallization activation energy of Ni-Mn-In thin film has been determined by the Kissinger equation.The first-principles calculation results show that the saturation magnetic moments of Ni-Mn-In-Co increase with increasing Co content.In addition,as the content of Co substituted Ni increases,the total energy difference between the paramagnetic state and the ferromagnetic state of parent phase increases.This is the origin of increasing the Curie temperature of Ni-Mn-In by Co doping.Moreover,the stability of parent phase increases with increasing Co content,leading to the decreases of martensitic transformation temperature.