Magnetic and transport properties of as-prepared Mn2CoGa

Magnetic and transport properties of as-prepared Mn₂CoGa polycrystalline Heusler alloy were investigated. Results of magnetic measurements were found to agree well with literature data, i.e., the studied Mn₂CoGa is a ferrimagnet with magnetic moment of 2.03 μ_B/f.u. and a high Curie temperature T_C = 728 K. Measurements of transport properties revealed that electrical resistivity ρ of Mn₂CoGa is anomalously large (∼250 µΩ·cm at room temperature) and demonstrates a complex temperature dependence. Specifically, in the measured temperature interval from 80 K to 375 K, the electrical resistivity is proportional to T² up to T ∼ 200 K while at higher temperatures ρ can be fitted by ρ(T) = A + B·exp(−CT) expression. These changes in the scattering mechanisms are accompanied by a change of the magnetoresistance sign from positive at T below ∼200 K to negative at higher temperatures.