H. Ghosh et al., COEXISTENCE OF BAND JAHN-TELLER DISTORTION AND SUPERCONDUCTIVITY IN CORRELATED SYSTEMS, Physical review. B, Condensed matter, 57(21), 1998, pp. 13414-13417
The coexistence of the band Jahn-Teller (BJT) effect with superconduct
ivity (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 created in th
e slave boson formalism and the interorbital Coulomb repulsion treated
in the Hartree-Fock mean field approximation, describes the correlate
d system. The model further incorporates the BJT interaction and a pai
ring term to account for the lattice distortion and superconductivity,
respectively. It is found that structural distortion tends to suppres
s superconductivity and when SC sets in at low temperatures, the growt
h of the lattice distortion is arrested. The phase diagram comprising
of the SC and structural transition temperatures T-c and T-s versus th
e dopant concentration delta reveals that the highest obtainable T-c f
or an optimum doping is limited by structural transition. The dependen
ce of the occupation probabilities of the different bands as well as t
he density of states in the distorted-superconducting phase, on electr
on correlation has been discussed.