Dimerized spin model of superconductivity

Yamaji K., Yukihiro Shimoi

Marric Stephens

Masatoshi Imada

A mechanism of superconductivity coming from the doping of mobile fermions into the spin dimerized insulator such as spin Peierls state, valence bond glass, Heisenberg spins with next nearest neighbor exchange coupling and the Haldane gap state is discussed. The doping of fermions with narrow band into a Mott insulator with a spin gap results in the superconducting long range order in two- and three-dimensions, while results in the power law divergence of the pairing susceptibility with Tomonaga-Luttinger liquid character of charge in one-dimension. An example of numerical calculation in one-dimension is shown. The possible relevance of this mechanism to high-temperature superconductivity, where dynamical coupling of lattice distortion to spin may play a crucial role, is discussed. A relevant model Hamiltonian with spin-phonon coupling and dynamical spin-Peierls fluctuation is proposed.

T. Kimura, Kazuhiko Kuroki, Ryotaro Arita +1 more

Possibility of superconductivity from electron repulsion in the Shastry-Sutherland lattice, which has a spin gap at half filling, is explored with the repulsive Hubbard model in the fluctuation-exchange approximation. We find that, while superconductivity is not favored around the half filling, superconductivity is favored around the quarter filling. Our results suggest that the Fermi-surface nesting is more important than the spin dimerization for superconductivity.

Richard M. Friedberg, T.D. Lee

N. N. Bogolyubov