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

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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. Tc resulting from interlayer pairing hopping can lead to a universal relation, when Tc is scaled by Tmaxc. Systematic reduction of superfluid density and increase of (Δd)max/KBTc ratio below and near optimal doping have their natural explanation in our picture. A crossover temperature T⁰ found in some of magnetic experiments such as NMR is also easily understood in the present framework.