Prediction of a supersolid phase in high-pressure deuterium

TL;DR

This study provides computational evidence for a supersolid phase in high-pressure deuterium, showing coexistence of crystalline order and superfluidity at low temperatures, which advances understanding of this elusive state of matter.

Contribution

First demonstration of a supersolid phase in deuterium under high pressure using bosonic path integral molecular dynamics simulations.

Findings

Observation of atomic exchange processes with preserved crystalline order

Detection of Bose-Einstein condensation at zero temperature

Finite superfluid fraction indicating supersolidity

Abstract

Supersolid is a mysterious and puzzling state of matter whose possible existence has stirred a vigorous debate among physicists for over 60 years. Its elusive nature stems from the coexistence of two seemingly contradicting properties, long-range order and superfluidity. We report computational evidence of a supersolid phase of deuterium under high pressure ($p >800$ GPa) and low temperature (T $<$ 1.0 K). In our simulations, that are based on bosonic path integral molecular dynamics, we observe a highly concerted exchange of atoms while the system preserves its crystalline order. The exchange processes are favoured by the soft core interactions between deuterium atoms that form a densely packed metallic solid. At the zero temperature limit, Bose-Einstein condensation is observed as the permutation probability of $N$ deuterium atoms approaches $1/N$ with a finite superfluid fraction. Our study provides concrete evidence for the existence of a supersolid phase in high-pressure deuterium and could provide insights on the future investigation of supersolid phases in real materials.