Electronic structure and magnetism of YCo4B and YCo3B2

Electronic structures of YCo4B and YCo3B2 are calculated in a self-consistent linear muffin-tin orbital method and the atomic sphere approximation. The effects of B atom in these compounds are discussed, by comparing the calculated local density-of-states curves with those of YCo5 obtained previously. A good agreement between the calculated and observed values of the low-temperature specific heat coefficient for YCo3B2 is obtained. Spin-polarized band calculations are also carried out and the local spin and orbital magnetic moments are evaluated at each Co atom site in YCo4B. It is found that the Co moment on 6i site is small, while the Co moment on 2c site is large. On the other hand, YCo3B2 is found to be non-magnetic. These results are consistent with the observed ones and can be explained by the mixing model between 3d-states of Co and 2p-states of B. (orig.)