Magnetic properties and phase stability of Half-metal-type ferromagnetic Co-based Heusler alloys of Co₂ (Cr_1–xMn_x) Ga

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Phase diagram and magnetic properties of Co₂ (Cr_1–xMn_x) Ga Heusler alloys were experimentally established. Single phase was obtainable in the entire composition range, 0 ≤ x ≤ 1.0. Order–disorder phase transition temperature from L2₁ to B2 phase (T_t^L21/B2) and the Curie temperature (T_C) increased with increase of Mn composition, in other words, with increase of number of valence electrons (Z_t). The behavior of T_C is general trend in the Co-based Heuselr alloys that were systematically investigated previously, whereas the concentration dependence of T_t^L21/B2 doesn't follow the Bragg–Williams–Gorsky approximation in Co₂ (Cr_1–xMn_x) Ga alloys. Spontaneous magnetization also increases with increase of Z_t with following the generalized Slater–Pauling rule, suggesting that the half-metal-type electronic structure is comparatively kept in the system.