Coexistence of band Jahn-Teller distortion and superconductivity in correlated systems

Haranath Ghosh; Manidipa Mitra; S. N. Behera; S. K. Ghatak

doi:10.1103/PhysRevB.57.13414

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Coexistence of band Jahn-Teller distortion and superconductivity in correlated systems

Haranath Ghosh, Manidipa Mitra, S. N. Behera, S. K. Ghatak

DOI 10.1103/PhysRevB.57.13414 · Physical Review B

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Abstract

The coexistence of the band Jahn-Teller (BJT) effect with superconductivity (SC) is studied for correlated systems with orbitally degenerate bands using a simple model. The Hubbard model for a doubly degenerate orbital with the on-site intraorbital Coulomb repulsion treated in the slave boson formalism and the interorbital Coulomb repulsion treated in the Hartree-Fock mean field approximation, describes the correlated system. The model further incorporates the BJT interaction and a pairing term to account for the lattice distortion and superconductivity, respectively. It is found that structural distortion tends to suppress superconductivity and when SC sets in at low temperatures, the growth of the lattice distortion is arrested. The phase diagram comprising of the SC and structural transition temperatures Tc and Ts versus the dopant concentration δ reveals that the highest obtainable Tc for an optimum doping is limited by structural transition. The dependence of the occupation probabilities of the different bands as well as the density of states in the distorted-superconducting phase, on electron correlation has been discussed.