Determinant quantum Monte Carlo study of the enhancement ofd-wave pairing by charge inhomogeneity

Abstract

Striped phases, in which spin, charge, and pairing correlations vary inhomogeneously in the CuO 2 planes, are a known experimental feature of cuprate superconductors, and are also found in a variety of numerical treatments of the two-dimensional Hubbard Hamiltonian. In this paper, we use determinant quantum Monte Carlo to show that if a stripe density pattern is imposed on the model, the d-wave pairing vertex is significantly enhanced. We attribute this enhancement to an increase in antiferromagnetic order which is caused by the appearance of more nearly half-filled regions when the doped holes are confined to the stripes. We also observe a π -phase shift in the magnetic order.

Determinant quantum Monte Carlo study ofd-wave pairing in the plaquette Hubbard hamiltonian

“…17(a). In stark contrast to the plaquette model and to the striped V 0 model, 44 Γ d P d becomes positive when V 0 is turned on: the d-wave pairing vertex is made repulsive. As with the plaquette Hamiltonian of the previous sections, we are interested in how the dependence of pairing on inhomogeneity is affected by the density.…”

“…Thus this model makes partial contact with earlier studies of binding on CuO 2 clusters in the limit pd = 0. [5][6][7] Another point of contact of this model is to other inhomogeneity patterns which share an f = 1/4 proportion of sites with raised on-site energy, for example [44] in which a pattern of stripes was shown to enhance d-wave pairing away from half-filling. Results for this site-energy inhomogeneous geometry (f = 1/4) are shown in Fig.…”

“…built of two site dimers rather than four site clusters, 18 modulated by different site potentials 43 or consisting of lines of different chemical potentials, alternating between half-filled antiferromagnetic stripes and doped stripes has also been explored. 44 In this section we examine the effects on pairing of an inhomogeneity pattern in which the local energies on a regular pattern of sites is raised by an amount V 0 . That is, we add a term H = V 0 l∈A,σ n lσ to the Hubbard Hamiltonian Eq.…”

Pairing correlations in the two-layer attractive Hubbard model

“…Experimental studies of superconductivity in systems in which one layer (BaBiO 3 ) provides the electron pairing interaction and the other layer (BaPbO 3 ) is conducting, which test some of the ideas of [8,9] have also been reported. Indeed, the role of inhomogeneity, arising either spontaneously or introduced explicitly into the Hamiltonian, has been studied in a variety of contexts within the repulsive Hubbard model as well [10,11].…”

Dynamical mean-field theory study of stripe order and d -wave superconductivity in the two-dimensional Hubbard model

“…In addition, an analysis of the energetics for the different stripe wavelengths for a wide region of doping values has been missing. Several works have also investigated superconductivity coexisting with inhomogeneities induced by various external potentials [70][71][72][73], but it is not clear if such studies are relevant for the stripe states with spontaneous translational symmetry breaking.…”