Galvanomagnetic properties of Heusler alloy Co2YAl (Y = Ti, V, Cr, Mn, Fe, and Ni)

Resumo

The Hall effect and the magnetoresistance of ferromagnetic Heusler alloys Co₂YAl, where Y = Ti, V, Cr, Mn, Fe, and Ni have been studied at T = 4.2 K in magnetic fields H ≤ 100 kOe. Normal R₀ and anomalous R_S Hall coefficients are shown to be maximal in magnitudes in the middle of the 3d period of the periodic table of elements. Coefficient R₀ changes the negative sign to positive sign in going from weak (Y = Ti, V) to strong (Y = Cr, Mn, Fe, and Ni) ferromagnetic alloys. Constant R_S is positive and proportional to ρ^2.9 in all the alloys. The magnetoresistance of the alloys is not higher than several percent and its magnitude is changed fairly significantly in the dependence on the number of valence electrons z; the magnetoresistance signs vary arbitrarily.