Electronic structure of perovskite related La₂CuSnO₆

The band structure of La₂CuSnO₆ in both its real and idealized crystal structure was determined using the local density full-potential linearized muffin-tin orbital (LMTO) method. Unlike the case for all other high-T_c copper-based materials, the Fermi energy for the undoped crystal is located exactly on the van Hove saddle-point singularity, which may be the main reason for the lattice distortions observed in the real material. We suggest that a possible way, if any, to drive this compound into the superconducting state is to be achieved via electron doping. For several reasons, we do not expect a high T_c value.