Magnetic states of Gd2Co2Al and Gd2Co2Ga with the W2Co2B-type structure

Electronic band structures of the W2Co2B-type Gd2Co2Al and Gd2Co2Ga compounds are calculated by self-consistent spin-polarized linear muffin-tin orbital (LMTO) method, within a local spin density approximation (LSDA) frame. The calculation results indicate that the magnetic moments of Gd and Co are antiferromagnetic coupled via the 3d-5d interaction in these compounds. The Co magnetic moment is induced by the exchange field of the ferromagnetically ordered Gd3+ in these compounds. All the ground states are shown to be ferrimagnetic by the total electronic energy calculations. Very good agreement between the calculated and experimental values for the lattice constants and magnetic moments is obtained for Gd2Co2Al and Gd2Co2Ga compounds.