Electronic structure of TbBa2 Cu3 O7

Abstract

The full-potential linearized augmented plane wave (FP-LAPW) method was used for spin-polarized electronic structure calculations of stoichiometric TbBa 2 Cu 3 O 7 (Tb123), not synthesized as a single phase yet. The generalized gradient approximation plus Hubbard correction (GGA + U) was employed for Tb4f electrons to prevented fractional occupation of states at Fermi level and hybridization with other electrons. The determined band structure is Y123-like with the metallic character as in the other superconducting R123 (R = rare earth). The presented results indicate that strong on-site spin moment of Tb could not effectively influence the neighbours and the induced magnetic interactions in the system are weak (CuO planes) or negligible (BaO planes and CuO chains). This appears to be the repercussion of the 'size effect' due to relatively small Tb +3 ionic radius. The predicted weak influence of magnetic moments of Tb on CuO states in the assumed (hypothetical) Fermi liquid phase of TbBa 2 Cu 3 O 7 could favour the rise of superconductivity in this system.