Low-temperature hall effect and martensitic transition temperatures in magnetocaloric Ni50Mn35Sb15−xGex (x = 0, 1, 3) alloys

Abstract

The field dependence of Hall resistivity ρH and magnetization M of the magnetocaloric Ni50Mn35Sb15−xGex (x = 0, 1, 3) alloys were measured at T = 4.2 K and in magnetic fields of up to 70 kOe. The martensitic transitions temperatures, i.e., the martensite start temperature MS, martensite finish temperature MF, austenite start AS and austenite finish AF temperatures, were obtained from the magnetization temperature dependence that measured from 4.2 to 350 K in a field of 1 kOe. It was observed that the martensitic transitions temperatures correlate strongly both with the valence electron concentration e/a and with the electronic transport characteristics, which are the coefficients of normal R0 and anomalous RS Hall effect and the concentration of charge carriers n. Apparently, similar correlations should be observed in other magnetocaloric compounds that could be used to study martensitic transitions.