Static impurities in a supersolid of interacting hard-core bosons on a triangular lattice

TL;DR

This paper investigates how static impurities influence the coexistence of solid and superfluid orders in a supersolid phase of hard-core bosons on a triangular lattice, revealing complex interactions and impurity-induced phase transitions.

Contribution

It demonstrates the unique effects of static vacancies on the order parameters in a supersolid, highlighting impurity-induced enhancement and phase separation phenomena.

Findings

Impurities reduce order parameters in solid and superfluid phases.

In supersolids, impurities simultaneously affect both order parameters.

An impurity pinning effect causes a first-order transition in the solid phase.

Abstract

We study the effect of impurities in a supersolid phase in comparison to the behavior in the solid and superfluid phases. A supersolid phase has been established for interacting hardcore bosons on a triangular lattice which may be realizable by ultracold atomic gases. Static vacancies are considered in this model which always lower the magnitude of the order parameter in the solid or superfluid phases. In the supersolid phase, however, the impurities directly affect both order parameters simultaneously and thereby reveal an interesting interplay between them. In particular the solid order may be enhanced at the cost of a strong reduction of the superfluidity, which shows that the two order parameters cannot be in a simple superposition. We also observe an unusual impurity pinning effect in the solid ordered phase, which results in two distinct states separated by a first-order transition.