Magnetic and electrical properties of the half-metallic ferromagnets Co$_2$CrAl

This paper presents the results of measurements of the magnetic and electrical properties of the ferromagnetic alloy Co$_2$CrAl in two structural states: (i) after severe plastic deformation and (ii) after shortterm high-temperature annealing of the deformed specimens. The experiments have been performed at temperatures in the range from 2 to 900 K in magnetic fields $H\le$ 50 kOe. The ferromagnetic Curie temperature $T_C$ and the paramagnetic Curie temperature $\Theta$ have been determined ($T_C$ = 305 K and $\Theta$ = 326 K), as well as the spontaneous magnetic moment $\mu_S$ and the effective magnetic moment $\mu_{\mathrm{eff}}$ per molecule of the alloy ($\mu_S$ = 1.62 $\mu_{\mathrm{B}}$ and $\mu^2_{\mathrm{eff}}$ = 8.2 $\mu_{\mathrm{B}}^2$). It has been shown that the magnetic crystalline anisotropy energy of the alloy is on the order of $\sim$5 $\times$ 10$^5$ erg/g. The specific features of the electrical properties are associated with the presence of an energy gap in the electronic spectrum near the Fermi level EF and with the change in the parameters of the energy gap as a function of the temperature.