Self-localization of a single hole in Mott antiferromagnets

TL;DR

This study uses large-scale numerical simulations to demonstrate that a single hole in ladder-shaped Mott antiferromagnets becomes self-localized, challenging the quasiparticle picture and supporting phase string theory.

Contribution

First numerical evidence showing self-localization of a single hole in ladder Mott antiferromagnets, confirming phase string theory predictions and highlighting strong correlation effects.

Findings

Single hole is localized in ladder systems with more than one leg.

Quasiparticle weight vanishes for the localized hole.

Localization length decreases with increasing leg number.

Abstract

A long-standing issue in the physics of strongly correlated electronic systems is whether the motion of a single hole in quantum antiferromagnets can be understood in terms of the quasiparticle picture. Very recently, investigations of this issue have been within the experimental reach. Here we perform a large-scale density matrix renormalization group study, and provide the first unambiguous numerical evidence showing that in ladder systems, a single hole doped in the Mott antiferromagnet does not behave as a quasiparticle. Specifically, the injected hole is found to be always localized as long as the leg number is larger than one, with a vanishing quasiparticle weight and a localization length monotonically decreasing with the leg number. In addition, the single hole self-localization is insensitive to the parity (even-odd) of the leg number. Our findings may advance conceptual developments in different fields of condensed matter physics. First of all, the intriguing self-localization phenomenon is of pure strong correlation origin free of extrinsic disorders. Therefore, it is in sharp contrast to the well-known Anderson localization and recently found many-body localization, where extrinsic disordered potentials play crucial roles. Second, they confirm the analytical predictions of the so-called phase string theory, suggesting that the phase string effect lies in the core of the physics of doped Mott antiferromagnets.