Temperature derivative of the superfluid density and flux quantization as criteria for superconductivity in two-dimensional Hubbard models
- Physikalisches Institut, Universitaet Wuerzburg, 97074 Wuerzburg (Germany)
- Department of Physics, University of California, Santa Barbara, California 93106-9530 (United States)
Based on extensions of quantum Monte Carlo algorithms to incorporate magnetic fields, two criteria to detect superconductivity in two-dimensional Hubbard models are investigated. We calculate both the internal energy [ital E]([Phi],[ital T]) as well as the ground-state energy, [ital E][sub 0]([Phi]), for Hubbard models on a cylinder geometry threaded by a flux [Phi]. The temperature derivative of the superfluid density, [partial derivative][beta][ital D][sub [ital s]]([beta])/[partial derivative][beta], is obtained from the difference in internal energy of systems which differ by a phase twist [pi]/2 in the boundary condition along one lattice direction. In the framework of a Kosterlitz-Thouless transition, [partial derivative][beta][ital D][sub [ital x]]([beta])/[partial derivative][beta] scales to a Dirac [delta] function at the transition temperature. On finite-sized lattices, [partial derivative][beta][ital D][sub [ital s]]([beta])/[partial derivative][beta] shows a response which increases with lattice size. From the functional form of [ital E][sub 0]([Phi]), superconducting or nonsuperconducting ground states may be identified. In both approaches, superconductivity may be detected without prior knowledge of the symmetry and nature of the pairing correlations. For single-band Hubbard models, our results include numerical data which (a) confirm the existence and pin down the transition temperature of a Kosterlitz-Thouless-type transition in the attractive Hubbard model away from half-band filling and (b) show that the quarter-filled repulsive Hubbard model is not superconducting. For the three-band Hubbard model we consider two parameter sets which take into account the differences in static magnetic structure and Fermi surfaces between La-Sr-Cu-O and Y-Ba-Cu-O materials. For both parameter sets, the finite-temperature approach showed no sign of a Kosterlitz-Thouless-type transition up to inverse temperatures [beta]=17.5, in units of Cu-O hopping.
- OSTI ID:
- 6903794
- Journal Information:
- Physical Review, B: Condensed Matter; (United States), Journal Name: Physical Review, B: Condensed Matter; (United States) Vol. 50:17; ISSN PRBMDO; ISSN 0163-1829
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
CALCULATION METHODS
CRYSTAL MODELS
ELECTRIC CONDUCTIVITY
ELECTRICAL PROPERTIES
FLUX QUANTIZATION
HUBBARD MODEL
KOSTERLITZ-THOULESS THEORY
MAGNETIC FLUX
MATHEMATICAL MODELS
MONTE CARLO METHOD
NUCLEAR MODELS
PHYSICAL PROPERTIES
SUPERCONDUCTIVITY
SUPERFLUID MODEL
TWO-DIMENSIONAL CALCULATIONS