Fermi surfaces of CeCu6 and CeCu2Si2

The energy band structures and Fermi surfaces are calculated for CeCu6 and LaCu2Si2, which are well known as a heavy-fermion compound, and the reference material CeCu2Si2, using a relativistic linearized APW method within the local density approximation. Both the present calculation for CeCu6 and our previous calculation for LaCu6 cannot explain the experimental signals of the de Haas-van Alphen (dHvA) effect for CeCu6. The measured dHvA result for CeCu2Si2 shows a cylindrical surface in the ac-plane above the magnetic transition field. The calculated Fermi surface of LaCu2Si2 explains the experiments for CeCu2Si2 better than our previous results of CeCu2Si2, in which the 4f-electrons on Ce are treated as itinerant. Therefore the 4f-electrons on Ce in CeCu2Si2 are well localized and do not affect the Fermi surface significantly in an applied magnetic field. (orig.)