Galvanomagnetic properties of Heusler alloy Co$_{2}Y$Al ($Y$ = Ti, V, Cr, Mn, Fe, and Ni)

The Hall effect and the magnetoresistance of ferromagnetic Heusler alloys Co$_{2}Y$Al, where $Y$ = Ti, V, Cr, Mn, Fe, and Ni have been studied at $T$ = 4.2 K in magnetic fields $H\le$ 100 kOe. Normal $R_0$ and anomalous $R_S$ Hall coefficients are shown to be maximal in magnitudes in the middle of the 3$d$ period of the periodic table of elements. Coefficient $R_0$ 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 $\rho^{2.9}$ 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.