Influence of Annealing Conditions on Structure and Critical Parameters of Ni50Mn37Sn13 Magnetocaloric Material

Abstract

In this paper, we present the influence of annealing conditions on structure and magnetic behavior of Ni$_{50}$Mn$_{37}$Sn$_{13}$ magnetocaloric alloy prepared by arc-melting technique. The results show that the almost single phase of the full Heusler structure of Ni$_{2}$MnSn could be achieved by appropriate annealing. The transformation between martensite and austenite phases, and multi-magnetic phase behavior are observed more clearly with higher fraction of Ni$_{2}$MnSn phase. By using Arrott-Noaks method, critical parameters were determined to be $\beta   0.464 \pm  0.021$, $\gamma  = 1.117 \pm  0.073$ and $\delta  = 3.41$, which lay between mean-field model ($\beta  = 0.5$ and $\gamma = 1$, $\delta  = 3$) with long-range ferromagnetic orders and 3D Heisenberg model ($\beta  = 0.365$, $\gamma = 1.336$, $\delta {\rm g}= 4.66$) with short-range ferromagnetic orders. The calculated results are in good accordance with the experimentally observed coexistence of weak-ferromagnetic martensite and strong-ferromagnetic austenite phases.