Superconducting Condensation Energy of the Two-Chain Hubbard Model in the Bulk Limit : Condensed Matter: Electronic Properties, etc.

概要

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We have studied on the possibility of superconductivity in the two-chain Hubbard model by using the variational Monte Carlo method changing the interchain transfer energy t_d. The energy gain per site ΔE in the variational BCS state in reference to the normal state energy, which is nothing but the superconducting condensation energy, was computed. We have fitted ΔE as a function of the inverse of the lattice size by a power-law function and found that in the bulk limit ΔE remains finite in a certain narrow range of t_d. Calculated momentum distribution functions reveal that the superconductivity is most stable in the case where the electron distribution in k-space is in a one-band-like situation, on the brink of transition to a two-band-like one. The SDW-type trial wave function was also examined but we did not obtain any energy gain with it in the above-mentioned superconducting region.
社団法人日本物理学会の論文
2000-07-15