Electronic structure and hyperfine interactions of T, T* and T' phases of (La1-xGdx)2Cu1-yFeyO4

Electronic structures and hyperfine interactions associated with the Cu-O environment of T, T*, and T' phases of (La1-xGdx)2CuO4 were studied, using the density functional theory in an embedded cluster approach. Mossbauer isomer shifts, electric field gradients and contact hyperfine fields for Fe-substituted species were determined for comparison with experiments performed on Fe:(La, Gd)1.85Sr0.15CuO4. These data are used to describe the response of charge and spin densities around Cu sites to sixfold (T), fivefold (T*), and fourfold (T') oxygen coordination. (author)