Spectral evolution with doping of an antiferromagnetic Mott state

Abstract

Since the discovery of half-filled cuprate to be a Mott insulator, the excitation spectra above the chemical potential for the unoccupied states has attracted many research attentions. There were many theoretical works using different numerical techniques to study this problem, but many have reached different conclusions. One of the reasons is the lack of very detailed high-resolution experimental results for the theories to be compared with. Recently, the scanning tunneling spectroscopy (STS)[1, 2] on lightly doped Mott insulator with an antiferromagnetic (AFM) order found the presence of in-gap states with energy of order half an eV above the chemical potential. The measured spectral properties with doping are not quite consistent with earlier theoretical works. In this paper we perform a diagonalization method on top of the variational Monte Carlo (VMC) calculation to study the evolution of AFM Mott state with doped hole concentration in the Hubbard model (HM). Our results found in-gap states that behave similarly with ones reported by STS. These in-gap states acquire a substantial amount of dynamical spectral weight transferred from the upper Hubbard band. The in-gap states move toward chemical potential with increasing spectral weight as doping increases. Our result also provides information about the energy scale of these in-gap states in relation with the coulomb coupling strength U.

Imaging the atomic-scale electronic states induced by a pair of hole dopants in Ca2CuO2Cl2 Mott insulator

“…The first finding is the transfer of spectral weight from high energy to low energy, leading to a peak within the CTG. This is characteristic of doped charges in Mott insulator, as has been interpreted theoretically [26][27][28]. However, although the local hole density increases continuously with decreasing pair distance, the peak position shows a sudden drop near 4 a0.…”

Enhancement of maximum superconducting temperature by applying pressure and reducing the charge transfer gap

“…On the contrary, there is no correlation for g = 1. The Jastrow-type factor [58] Pdh is introduced to provide an attractive interaction between doublon and hole [59][60][61] to make sure at half-filling we recover the Mott insulator without free carrier, it is of the form…”

Effect of Impurity on the Doping-Induced in-Gap States in a Mott Insulator

“…The key features of the in-gap states could be reproduced by numerical calculations based on the cluster perturbation theory [33] and the variational Monte Carlo simulations. [34] More recently, the LDOS in Ca 2 CuO 2 Cl 2 with a Ca vacancy is measured by STM. [7] Similar to the system with a Cl defect, the in-gap states were also found to localize around the Ca vacancy and vary at different sites.…”