Magnetization, electrical resistivity, magnetoresistance, and Hall resistivity of $\mathrm{N}{\mathrm{i}}_{50}\mathrm{M}{\mathrm{n}}_{35}\mathrm{I}{\mathrm{n}}_{14.25}{\mathrm{B}}_{0.75}$ and $\mathrm{N}{\mathrm{i}}_{50}\mathrm{M}{\mathrm{n}}_{35}\mathrm{I}{\mathrm{n}}_{14.5}{\mathrm{B}}_{0.5}$ Heusler alloys were studied in a temperature range $T=80–400\mathrm{K}$ in magnetic fields up to 20 kOe. Both alloys exhibit a martensitic transformation from a high-temperature ferromagnetic austenite phase to a low-temperature, low-magnetization martensitic phase. The electrical resistivity nearly doubles as a result of the martensitic transformation, reaching 180 and 100 µΩ cm in the martensitic states of $\mathrm{N}{\mathrm{i}}_{50}\mathrm{M}{\mathrm{n}}_{35}\mathrm{I}{\mathrm{n}}_{14.25}{\mathrm{B}}_{0.75}$ and $\mathrm{N}{\mathrm{i}}_{50}\mathrm{M}{\mathrm{n}}_{35}\mathrm{I}{\mathrm{n}}_{14.5}{\mathrm{B}}_{0.5}$, respectively. The temperature dependence of the electrical resistivity does not corresponded with the Mooij correlation. The magnetoresistance is negative with a narrow negative peak at the martensitic transition. Normal and anomalous Hall effect coefficients were determined by fitting the field dependences of the Hall resistivity using magnetization data. The coefficients of the normal Hall effect for both compositions were found to decrease with temperature from positive values in the austenite to negative values in the martensite phase. None of the known correlations between the anomalous Hall effect coefficient and resistivity were satisfied. Significant changes in the values of the anomalous Hall coefficients during the martensitic transformation are explained by the difference in spin-up and spin-down state occupations in the martensite and austenite phases. First-principles calculations of the electronic structures confirm this explanation.

• Received 28 November 2019
• Revised 28 February 2020
• Accepted 3 March 2020

DOI:https://doi.org/10.1103/PhysRevB.101.094423