Superconductivity and spin gap in the high-doping regime of a CuO chain model
National High Magnetic Field Laboratory, Florida State
University, 1800 E. Paul Dirac Dr., Tallahassee, Florida 32306, USA
2 Department of Physics, Norwegian University of Science and Technology, N-7034 Trondheim, Norway
Accepted: 9 October 1996
A two-band Hubbard model describing a CuO chain is studied using quantum Monte Carlo simulation. The Luttinger-liquid exponent is extracted as a function of the nearest-neighbor repulsion V, at hole fillings between 1 (half-filled lower band) and 2. Evidence is presented for the existence of a regime with dominant singlet superconducting fluctuations and a gap in the spin excitation spectrum at , in the neighborhood of the V for which the system phase separates. Closer to half-filling (), spin-density-wave fluctuations always dominate.
PACS: 71.27.+a – Strongly correlated electron systems / 71.30.+h – Metal-insulator transitions / 74.10.+v – Occurrence, potential candidates
© EDP Sciences, 1996