Existence of modulated structure and negative magnetoresistance in Ga excess Ni-Mn-Ga

Ni2-xMnGa1+x (0.4 <= x <= 0.9) show the existence of modulated crystal structure at room temperature (RT) in the martensite phase, exhibit ferromagnetic behavior and have high martensitic transition temperature. The saturation magnetic moment decreases as Ga content increases, and this is related to antisite defects between Mn and Ga atoms leading to Mn-Mn nearest neighbor antiferromagnetic interaction. Negative magnetoresistance is observed at RT that increases linearly with magnetic field. These properties of Ga excess Ni-Mn-Ga show that it is a potential candidate for technological applications. (C) 2011 American Institute of Physics. [doi: 10.1063/1.3604015]