Coexisting ordinary elasticity and superfluidity in a model of defect-free supersolid

TL;DR

This paper models a defect-free supersolid using the Gross-Pitaevskii equation, revealing coexistence of elasticity and superfluidity with unique rotational and stress responses.

Contribution

It introduces a defect-free supersolid model with coupled nonlinear equations, demonstrating novel mechanical behaviors without requiring defects or vacancies.

Findings

Non classical rotational inertia observed at low rotation speeds.

No superflow occurs under small stress or external force.

Matter flow appears only due to plasticity under finite stress.

Abstract

We present the mechanics of a model of supersolid in the frame of the Gross-Pitaevskii equation at $T=0K$ that do not require defects nor vacancies. A set of coupled nonlinear partial differential equations plus boundary conditions is derived. The mechanical equilibrium is studied under external constrains as steady rotation or external stress. Our model displays a paradoxical behavior: the existence of a non classical rotational inertia fraction in the limit of small rotation speed and no superflow under small (but finite) stress nor external force. The only matter flow for finite stress is due to plasticity.