Effect of partial substitution of In with Mn on the structural, magnetic, and magnetocaloric properties of Ni 2 Mn 1+x In 1-x Heusler alloys

The structural, magnetic and magnetocaloric properties of Ni2Mn1+xIn1-x alloys, prepared using an arc-melting furnace in an argon environment, have been studied for their potential application in cost-effective magnetic refrigeration technology. The room-temperature x-ray diffraction shows that the Ni2Mn1+xIn1-x alloys with 0 <= x <= 0.34 exhibit austenite cubic phase, whereas the alloys with x > 0.34 have mixed tetragonal martensite and cubic austenite phases. The Ni2Mn1.34In0.66 alloy shows a clear second-order phase transition with a Curie temperature of 305 K but its elemental composition is very close to the critical composition between first and second-order phase transitions. The calculated magnetic entropy change and relative cooling power of the Ni2Mn1.34In0.66 alloy measured at 3 T field are 4.5 J kg(-1) K-1 and 201 J kg(-1), respectively. The temperature dependent resistivity of Ni2Mn1.34In0.66 alloy measured at H = 0 Oe shows that the sample has a room temperature resistivity of rho= 7x 10(-7) Omega m. The absence of thermal and magnetic hysteresis due to second-order magnetic phase change, coupled with higher values of magnetic entropy change and relative cooling power, suggests that the Ni2Mn1.34In0.66 alloy has the potential for magnetic refrigeration.