Development of Superconducting Correlation at Low Temperatures in the Two-dimensional t-J Model(Condensed Matter : Electronic Structure, Electrical, Magnetic and Optical Properties)

概要

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The equal-time pairing correlation function of the two-dimensional t-J model on a square lattice is studied using a high-temperature expansion method. The sum of the pairing correlation, its spatial dependence, and the correlation length are obtained as functions of temperature down to T≃0.2t. By comparison of single-particle contributions in the correlation functions, we find an effective attractive interaction between quasi-particles in d_<x^2-y^2>-wave pairings. It is shown that d-wave correlation grows rapidly at low temperatures for 0.5<n<0.9, with n being the electron density. The temperature for this growth is roughly scaled by J/2. This is in sharp contrast to the Hubbard model in a weak or intermediate coupling region, where there is no numerical evidence of superconductivity.
社団法人日本物理学会の論文
2005-05-15