Electrical properties of half-metallic PtMnSb-based Heusler alloys

We have studied the electrical properties of the Heusler the alloys, PtMnSb, PdMnSb and PtGdBi, in relationship to the electronic band structures. Measurements of the electrical conductivity, Hall mobility and thermoelectric power for the alloys were performed in the temperature range from 77 to 850 K. From the results, it was found that PtMnSb and PdMnSb exhibit half-metallic conductivities, i.e., metallic for majority spin while semiconducting for minority spin bands, while PtGdBi is a narrow-gap semiconductor of p-type. The activation energy E/sub a/ of PtGdBi was found to be about 14 meV, which. Was obtained from the slope of the hole concentration p versus 1/T curve at low temperatures region up to 300 K. The energy gap E/sub G/ in PtGdBi could not be determined for the present. The values of electrical conductivity, Seebeck coefficient, mobility and hole concentration were also found to be of about 2/spl times/10/sup 3/ S/cm, 60 /spl mu/V/K, 120 cm/sup 2//Vs, and 7/spl times/10/sup 19/ cm/sup -3/ at room temperature, respectively.