Structural, magnetic, and magnetocaloric properties of the Ni 54 (FeMn) 19 Ga<sub>27 heusler alloy

Abstract

The structural, magnetic, and magnetocaloric properties of the Ni-54(FeMn)(19)Ga-27 Heusler alloy have been presented, which has both Fe and Mn atoms at the 4a site of its austenite structure. The alloy is compared with the ternary alloys of the Ni54Fe19Ga27 and the Ni54Mn19Ga27. The alloy has a mixed-phase, which is L2(1) cubic and 14 M tetragonal at room temperature. The temperature-dependent magnetization curve exhibits ferromagnetic to paramagnetic phase transition in the range of 380-450 K. The obtained Curie temperature is 384 K. Fe and Mn are located at 4a site with the excess Ni and Ga in the non-stoichiometric alloy and therefore, ferromagnetic and antiferromagnetic interactions cause the decrease in the magnetization of the alloy and the Fe-Mn and Ni-Mn interactions led to high Curie temperature compared with that of both the Ni54Fe19Ga27 and Ni54Mn19Ga27. The saturation magnetization of the alloy is 53.97 Am(2)kg(-1) under 2 T magnetic field at room temperature. The hysteresis curve is narrow and the coercivity is 0.19 mT under 2 T, and the alloy is a soft magnetic material. The Arrott plot curves indicate that the alloy shows the second-order phase transition and the magnetic entropy change is about 1.5 J kg(-1)K(-1) under 2 T magnetic field.