Sliding phase in randomly stacked 2D superfluids/superconductors

TL;DR

This paper uses quantum Monte Carlo simulations to study how weak Josephson tunneling affects layered 2D superfluids, revealing a novel sliding phase with unique coherence properties in disordered systems.

Contribution

It demonstrates the emergence of a sliding phase in disordered layered superfluids, a phenomenon not previously characterized in detail.

Findings

Weak tunneling enhances critical temperature and induces 3D coherence in clean systems.

Disorder leads to a sliding phase with 2D superflow but no transverse coherence.

Critical properties of the sliding regime are thoroughly analyzed.

Abstract

Using large scale quantum Monte Carlo simulations of lattice bosonic models, we precisely investigate the effect of weak Josephson tunneling between 2D superfluid or superconducting layers. In the clean case, the Kosterlitz-Thouless transition immediately turns into 3DXY, with phase coherence and superflow in all spatial directions, and a strong enhancement of the critical temperature. However, when disorder is present, rare regions fluctuations can lead to an intermediate finite temperature phase --- the so called sliding regime --- where only 2D superflow occurs within the layers without any transverse superfluid coherence, while a true 3D Bose-Einstein condensate exists. Critical properties of such an unconventional regime are carefully investigated.