Magnetic and thermal properties of Ni-Mn-Ga shape memory alloy with Martensitic transition near room temperature

We have studied the magnetic properties of an off-stoichiometric Heusler shape memory alloy Ni51.9Mn23.2Ga24.9 with near room temperature martensitic transition at 306 K. The temperature dependence of magnetization revealed a thermal hysteresis and a ∼10% decrease in spontaneous magnetization across the martensitic transition. In-situ X-ray diffraction measurements at different temperatures revealed a negative shape strain of 4.8%. Heat absorptions measurements indicated that the martensitic structural transition may take place in multiple steps.