Magnetic properties of SmCo5 and YCo5

We have studied the magnetic moments and magnetic anisotropy energy (MAE) of YCo5 and SmCo5 using full-potential linear augmented plane wave (LAPW) electronic structure calculations. Most previous calculations of the MAE for YCo5, using local density approximation (LDA) for the exchange-correlation potential, have found values significantly smaller (similar to0.6 meV/f.u.) than experiment (similar to3.8 meV/f.u.). The rest of the MAE is attributed to many body corrections. Our LAPW calculations using the generalized gradient approximation (GGA) instead of LDA and including nonspherical corrections give values similar to1.5 meV/f.u. The Co magnetic moment of YCo5-xCux, unlike the prediction of the virtual crystal approximation, decreases slowly with impurity concentration until dropping suddenly to zero at a critical dopant concentration. Correlation effects were found to be crucial for the MAE in SmCo5. While GGA calculations give MAE for SmCo5 of the wrong sign, including the LDA+U, correction brings it to similar to21 meV/f.u., in good agreement with the experimental value of 13-16 meV/f.u. (C) 2003 American Institute of Physics.