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Temperature dependences of electrical resistivity of Co2MnZ (Z = Al, Si, Ga, Ge, Sn) Heusler alloys were measured in a temperature range of 78–300 K; their magnetization was measured at 5 and 300 K in fields up to 30 kOe. It was found that, for the Co2MnAl and Co2MnGa alloys, the Mooij rule [Mooij J.H. Phys. Stat. Sol. (a). 1973. V. 17. P. 521] does not hold. A correlation between electronic and magnetic characteristics of the Co2MnZ alloys and atomic number of element Z is found. [ABSTRACT FROM AUTHOR]

The residual resistivity, Hall effect, and magnetization of Co2YSi (Y = Ti, V, Cr, Mn, Fe, Co, Ni) Heusler alloys were considered at T = 4.2 K and in fields up to 100 kOe. It is shown that as the number of valence electrons z ranges from 26 to 32, significant changes in the residual resistivity ρ0, magnetization Ms, sign and magnitude of the normal R0 and anomalous RS Hall effect coefficients are observed during the transition from Co2TiSi to Co2NiSi. It is established that there is a clear correlation between the values ρ0, R0, RS and Ms, depending on the number z, which can be associated with the appearance of a half-metal ferromagnetic state and/or spin gapless semiconductor. As z changes, the anomalous Hall effect coefficient has a power-law dependence on the residual electrical resistivity with an exponent of k = 3.1, which diverges with existing theories but agrees well with the experimental data obtained earlier for similar half-metallic ferromagnetic Heusler alloys. [ABSTRACT FROM AUTHOR]