Nature of the inhomogeneous state of the extended t-J model on a square lattice

TL;DR

This study uses variational Monte Carlo methods to explore inhomogeneous states in the extended t-J model on a square lattice, revealing distinct stripe patterns and magnetic orders in hole- and electron-doped cuprates.

Contribution

It introduces a generalized t-J model including electron-phonon effects and identifies new stripe structures and magnetic phases in doped cuprates.

Findings

Hole-doped cuprates exhibit d-wave superconductivity with AF-RVB stripe patterns.

Electron-doped cuprates show in-phase magnetic domain stripes with long-range AF order.

Presence of IPMD stripes suggests possible electronic phase separation in electron-doped materials.

Abstract

We carry out the variational Monte Carlo calculation to examine spatially inhomogeneous states in hole- and electron-doped cuprates. By using Gutzwiller approximation, we consider the excitations, arising from charge density, spin density and pair field, of the mean-field ground state of the t-J model. It leads to the stripe patterns we have found numerically in a generalized t-J-type model including mass renormalization from the electron-phonon coupling. In the hole-doped side, a robust d-wave superconducting order results in the formation of the half-doped antiferromagnetic resonating-valence-bond (AF-RVB) stripes shown by the well-known Yamada plot. On the other hand, due to a long-range AF order in electron-doped materials, a stripe structure with the "in-phase" magnetic domain (IPMD) is obtained in the underdoped regime instead of the AF-RVB stripe. The IPMD stripe with the largest period permitted by lattice size is stabilized near the underdoped region and it excludes the Yamada plot from electron-doped cases. Based on finite lattice size to which we can reach, the existence of IPMD stripes may imply an electronic phase separation into an electron-rich and an insulating half-filled AF long-range ordered domains in electron-doped compounds.