Charge and spin structures of a dx2−y2 superconductor in the proximity of an antiferromagnetic Mott insulator

Abstract

To the Hubbard model on a square lattice we add an interaction W that depends upon the square of a near-neighbor hopping. We use zero-temperature quantum Monte Carlo simulations on lattice sizes up to 16×16, to show that at half-filling and constant value of the Hubbard repulsion, the interaction W triggers a quantum transition between an antiferromagnetic Mott insulator and a dx2−y2 superconductor. With a combination of finite-temperature quantum Monte Carlo simulations and the maximum entropy method, we study spin and charge degrees of freedom in the superconducting state. We give numerical evidence for the occurrence of a finite-temperature Kosterlitz-Thouless transition to the dx2−y2 superconducting state. Above and below the Kosterlitz-Thouless transition temperature, TKT, we compute the one-electron density of states N(ω), the spin relaxation rate 1/T1, as well as the imaginary and real part of the spin susceptibility χ(q→,ω). The spin dynamics are characterized by the vanishing of 1/T1 and divergence of Reχ(q→=(π,π),ω=0) in the low-temperature limit. As TKT is approached N(ω) develops a pseudogap feature and below TKTImχ(q→=(π,π),ω) shows a peak at finite frequency.

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