Magnetotransport properties of Ni-Mn-In Heusler Alloys: Giant Hall angle

Abstract

We report experimental results on phase transitions, magnetic properties, resistivity, and Hall effect in Ni50Mn50-xInx (15<x<16.2) Heusler alloys. Several distinguishing features of magnetotransport properties were clearly observed in the vicinity of the first order structural martensitic transition at TM and the ferromagnetic-paramagnetic transition at the Curie temperature TC of the austenitic phase. It was found that the Hall resistivity ρH(at H = 15 kOe) is positive in martensitic and negative in austenitic phase, sharply increases in the vicinity of TM up to ρH(15 kOe)= 50 μΩ·cm. This value is almost two orders of magnitude larger than that observed at high temperature (T~200K) for any common magnetic materials, and comparable to the giant Hall effect resistivity in magnetic nanogranular alloys. The Hall angle ΘH=tan- 1(ρH/ρ) close to TM reaches tan-1(0.5) which is the highest value for known magnetic materials.