Stripe order in the doped Hubbard model on the honeycomb lattice

TL;DR

This study uses DMRG and mean-field methods to reveal stripe order in the doped Hubbard model on a honeycomb lattice, advancing understanding of its ground state properties beyond half-filling.

Contribution

It demonstrates the presence of stripe order in the doped Hubbard model on honeycomb lattice, a novel insight into its ground state behavior.

Findings

Discovery of half-filled stripe order in doped system

Stripe states with near-degenerate energies

Confirmation via DMRG and mean-field calculations

Abstract

We study the ground state properties of the doped Hubbard model with strong interactions on honeycomb lattice by the Density Matrix Renormalization Group (DMRG) method. At half-filling, due to the absence of minus sign problem, it is now well established by large-scale Quantum Monte Carlo calculations that a Dirac semi-metal to anti-ferromagnetic Mott insulator transition occurs with the increase of the interaction strength $U$ for the Hubbard model on honeycomb lattice. However, an understanding of the fate of the anti-ferromagnetic Mott insulator when holes are doped into the system is still lacking. In this work, by calculating the local spin and charge density for width-4 cylinders with DMRG, we discover a half-filled stripe order in the doped Hubbard model on honeycomb lattice. We also perform complementary large-scale mean-field calculations with renormalized interaction strength. We observe half-filled stripe order and find stripe states with filling close to one half are nearly degenerate in energy.