New interpretation of slave boson mean-field theory of the $t-J$ model: short-range antiferromagnetic and d-wave pairing correlations

Abstract

The $t-J$ Hamiltonian is studied in a mean-field approximation by taking into account antiferromagnetic and d-wave pairing correlations. Considering the presence of antiferromagnetic fluctuations, the weaknesses of a mean-field approximation and the limitation of the $t-J$ model near half-filling, we give a new interpretation to the slave boson mean-field theory of the $t-J$ model. We argue that due to phase coherence-breaking antiferromagnetic fluctuations and quantum fluctuations, superconducting long-range order does not appear strictly in two dimensions. $T_c$ resulting from interlayer pairing hopping can lead to a universal relation, when $T_c$ is scaled by $T_c^{max}$. Systematic reduction of superfluid density and increase of $({\Delta }_d{)}_{max}/K_B{T}_c$ ratio below and near optimal doping have their natural explanation in our picture. A crossover temperature $T^0$ found in some of magnetic experiments such as NMR is also easily understood in the present framework.

8 pages, 2 figures