Stripe formation in high-T_csuperconductors

Abstract

The non-uniform ground state of the two-dimensional three-band Hubbard model for the oxide high-Tc superconductors is investigated using a variational Mont Carlo method. We examine the effect produced by holes doped into the antiferromagnetic (AF) background in the underdoped region. It is shown that the AF state with spin modulations and stripes is stabilized due to holes travelling in the CuO plane. The structures of modulated AF spins are dependent upon the parameters used in the model. The effect of boundary conditions is reduced for large systems. We show that there is a region where incommensurability is proportional to the hole density. Our results give a consistent description of stripes observed by the neutron scattering experiments based on the three-band model for the CuO plane.

Metallic State of the Three-Band Hubbard Model with Super-Lattice Structure

“…They have studied these long-period correlations by the numerical or analytical methods on the basis of the two-dimensional (2D) Hubbard models and have clarified that some long-period correlated states can be the ground states around certain fillings. [3][4][5][6][7][8][9][10][11][12] These theoretically predicted long-period correlation states are consistent with the stripe state deduced from the neutron scattering experiments. 13 The theoretical results on the basis of the 2D Hubbard models mean that the strong on-site interaction is enough to stabilize the stripe state near 1/8-filling as far as the ground state is considered.…”

Excitation spectra in doped high-Tc cuprates

“…The inhomogeneous ground state as well as the superconducting state in the underdoped region has been investigated intensively based on the two-dimensional (2D) Hubbard model [12][13][14][15]. Within the 2D Hubbard model, the linear dependence of d on x has been successfully explained by variational Monte Carlo (VMC) method [15], and furthermore the saturation of incommensurability d for xO0.125 is also consistent with those obtained by the VMC method.…”

Effective quantum variational Monte Carlo study of Hubbard model

“…Recently, the mechanism of superconductivity in high-temperature superconductors has been extensively studied in terms of the two-dimensional (2D) Hubbard model [1,2]. We have investigated the two-leg ladder [3][4][5] and 2D Hubbard model on the basis of a variational Monte Carlo method [6][7][8][9][10][11][12][13] for the Gutzwiller function. The superconducting condensation energy for the Hubbard model is in good agreement with that obtained from the specific heat measurements and the critical magnetic field [7,8,14].…”