Charge modulation as fingerprints of phase-string triggered interference

TL;DR

This paper reveals that charge modulations in doped Mott insulators originate from quantum interference effects caused by phase strings in the strong coupling limit, challenging traditional mean-field explanations.

Contribution

It introduces a quantum interference mechanism based on phase strings in the $t-J$ model, explaining charge order beyond mean-field theories.

Findings

Charge modulations are observed in DMRG solutions with phase strings.

Switching off phase strings removes charge modulations.

Constructive interference from phase strings causes self-localization and charge patterns.

Abstract

Charge order appears to be an ubiquitous phenomenon in doped Mott insulators, which is currently under intense experimental and theoretical investigations particularly in the high $T_c$ cuprates. This phenomenon is conventionally understood in terms of Hartree-Fock type mean field theory. Here we demonstrate a mechanism for charge modulation which is rooted in the many-particle quantum physics arising in the strong coupling limit. Specifically, we consider the problem of a single hole in a bipartite $t-J$ ladder. As a remnant of the fermion signs, the hopping hole picks up subtle phases pending the fluctuating spins, the so-called phase string effect. We demonstrate the presence of charge modulations in the density matrix renormalization group solutions which disappear when the phase strings are switched off. This form of charge modulation can be understood analytically in a path-integral language, showing that the phase strings give rise to constructive interferences leading to self-localization. When the latter occurs, left- and right-moving propagating modes emerge inside the localization volume and their interference is responsible for the real space charge modulation.