Electronic structure of GdX2 (XÂ =Â Fe, Co and Ni) intermetallic compounds studied by the GGAÂ +Â U method

The electronic and magnetic properties of the ferromagnetic laves-phase GdX2 (X = Fe, Co and Ni) intermetallic compounds were calculated by using an all-electron full-potential linear muffin-tin orbital method (FP-LMTO) within GGA and GGA + U. The so-called GGA + U method is applied to properly treat the Gd-4f electron in the electronic structure calculation. The GGA improves the agreement between experiments and calculations for the lattice constants; however the GGA + U overestimates them, but gives a better representation of the band structure, density of states and magnetic moments compared to GGA alone. The reduction of the Co and Ni magnetic moments in the GdCo2 and GdNi2 compared to that in pure metals is due to the different localization strength of the transition metal and the same reason in the enormous reduction of the Curie temperatures.