Topological phase separation in 2D hard-core Bose-Hubbard system away from half-filling

TL;DR

This paper predicts that doping a 2D hard-core boson system away from half-filling leads to topological phase separation involving charge order and superfluid regions, resembling behaviors seen in various condensed matter systems.

Contribution

It introduces the concept of topological phase separation in doped 2D hard-core boson systems, extending understanding beyond uniform supersolid phases.

Findings

Prediction of multi-center topological defect formation upon doping

Analogies with granular superconductors and quantum Hall systems

Long-wavelength behavior similar to complex condensed matter states

Abstract

We suppose that the doping of the 2D hard-core boson system away from half-filling may result in the formation of multi-center topological defect such as charge order (CO) bubble domain(s) with Bose superfluid (BS) and extra bosons both localized in domain wall(s), or a {\it topological} CO+BS {\it phase separation}, rather than an uniform mixed CO+BS supersolid phase. Starting from the classical model we predict the properties of the respective quantum system. The long-wavelength behavior of the system is believed to remind that of granular superconductors, CDW materials, Wigner crystals, and multi-skyrmion system akin in a quantum Hall ferromagnetic state of a 2D electron gas.