Electronic bandstructures on 5d-transition metal pyrochlore:: Cd2Re2O7 and Cd2Os2O7

The electronic bandstructure calculations for Cd2Re2O7 and Cd2Os2O7 are performed by using an FLAPW method based on the local density approximation, where the spin-orbit interactions are taken into account. It is found that the spin-orbit interaction changes significantly Re/Os-5d (t(2g)) band dispersion situated near the Fermi level. Cd2Re2O7 is a semi-metal, the Fermi level is located just in the valley, the specific heat coefficient is calculated as 2.7 mJ/K-2 mol Re and the carrier number is 0.039/cell in each hole and electron. The Re/Os-5d bands hybridize well with the O-p bands so that the Re/Os-5d component significantly appears even in the bottom of the wide O-p bands. Therefore, it is important to consider Re-5d O-p hybridization to investigate the physical properties of these compounds. (C) 2002 Elsevier Science Ltd. All rights reserved.