A New Mean-Field Superconducting Phase in Two-Dimensional t-J Model near Half-Filling

Abstract

A new superconducting phase is found in the two-dimensional t-J model near half-filling within the mean-field theory and Gutzwiller approximation. This state has a spatial dependence of order parameters which is interpreted as a mixing of the extended s-wave component with the finite total momentum in addition to the d_x²_-y²-wave symmetry. The origin of this peculiar pairing is investigated. There is no node in the gap function in the new state and possible experimental consequences are discussed.