The magnetothermal characterization of Ni-Cu-Mn-Sn alloy

Abstract

The substantial study presents the structural and magnetic phase transitions in the Ni46.8Cu2.5Mn36.5Sn14.3 alloy through AC susceptibility measurement and heat capacity measurement in a zero magnetic field. To check whether it was achieved, the homogeneous distribution in the alloy, secondary electron, and backscattered detector images from scanning electron microscopy measurements are performed. The bulk alloy has a structural phase transition (Martensitic transition) which is around 200 K and a magnetic phase transition in the vicinity of room temperature upon cooling. The martensitic transition temperatures are martensite start (Ms = 195 K) and martensite finish (Mf = 181 K) upon a cooling cycle; austenite start (As = 199 K) and austenite finish (Af = 213 K) upon a heating cycle, obtained from the temperature dependence of the AC susceptibility. Above the TC, the alloy appears to comply with the Curie-Weiss law, and paramagnetic susceptibility ensures the value of the effective paramagnetic moment (mu eff) of 2.1 mu B and the paramagnetic Curie temperature (theta P) of 297 K. In the Martensite region, the temperature of the second magnetic phase transition is visible between 100 and 175 K, which can be manipulated to be related to Martensite Curie temperature. The electronic Sommerfeld (gamma T) and phonon coefficient (beta T3) obtained from heat capacity measurements are found from fit function as 12.47 (+/- 0.09) mJ.mol-1. K-2 and 2.96 x 10-4 J.mol- 1.K-4 but these values are higher than Ni-Mn-Sn and smaller than Ni-Mn-Ga alloys. The assumption is that the inconsistency in the results realized by the addition of Cu may come from hybridization or ferromagnetic band splitting. The values of the density of states at Fermi level N (EF) and Debye temperature are calculated with the heat capacity data as 1.31 state/eV.atom and 297 +/- 2 K, respectively. Finally, the indirect adiabatic temperature varies by 2 K for an applied magnetic field of 1 T in the combined magnetic and heat capacity measurements. The findings reported via the study are carried out to support the literature and commensurate with similar findings.