Do Bose metals exist in Nature?

TL;DR

This paper explores the existence of a stable Bose metallic phase in low-dimensional bosonic systems, challenging the traditional view that such systems are only superfluid or insulating, and suggests potential stability in higher dimensions near Mott transitions.

Contribution

It demonstrates, through numerical and analytical methods, that a Bose metallic phase can exist in 1D and possibly in higher dimensions near Mott transitions.

Findings

Bose metallic phase is theoretically stable in 1D.

The phase can be distinguished from superfluid and insulator.

Potential for stable Bose metals in higher dimensions near Mott transition.

Abstract

We revisit the concept of superfluidity in bosonic lattice models in low dimensions. Then, by using numerical and analytical results obtained previously for equivalent spinless fermion models, we show that the gapless phase of 1D interacting bosons may be either superfluid or -remarkably- metallic and not superfluid. The latter phase -the Bose metal- should be, according to the mentioned results, a robust and stable phase in 1D. In higher dimensionalities we speculate on the possibility of a stable Bose metallic phase on the verge of a Mott transition.