Drastic violation of the basic correlation between the Hall effect and resistivity in the Heusler alloy Ni45Cr5Mn37In13

Abstract Two metamagnetic Heusler alloys based on Ni 45 Cr 5 Mn 37 In 13 with differing Mn concentrations (by 0.2 at. %) were studied using magnetization, resistivity, and Hall resistivity measurements. It is shown that this small variation in composition leads to fundamental changes in magnetic properties. Near the martensitic phase transitions, the anomalous Hall coefficient ( R S ) was found to increase with temperature while the resistivity (ρ) decreases. Thus, in the case of Ni 45 Cr 5 Mn 37 In 13 , the general correlation between R S and ρ, considered as applicable for all crystalline and amorphous ferromagnetic alloys, breaks down completely. We explain this behavior in the framework of an s-d model where it is assumed that the resistivity and anomalous Hall effect are determined by different groups of current carriers.