Non-classical Rotational Inertia in a Two-dimensional Bosonic Solid Containing Grain Boundaries

TL;DR

This paper investigates non-classical rotational inertia in a two-dimensional bosonic solid with grain boundaries, using a vortex line mapping to superfluidity, revealing abrupt NCRI increases linked to connected superfluid regions.

Contribution

It introduces a numerical approach to evaluate NCRI in bosonic systems via vortex line configurations and superfluid hydrodynamics near grain boundaries.

Findings

NCRI increases abruptly with formation of connected superfluid regions.

Superfluidity along grain boundaries significantly influences NCRI.

Implications for understanding supersolid phenomena are discussed.

Abstract

We study the occurrence of non-classical rotational inertia (NCRI) arising from superfluidity along grain boundaries in a two-dimensional bosonic system. We make use of a standard mapping between the zero-temperature properties of this system and the statistical mechanics of interacting vortex lines in the mixed phase of a type-II superconductor. In the mapping, the liquid phase of the vortex system corresponds to the superfluid bosonic phase. We consider numerically obtained polycrystalline configurations of the vortex lines in which the microcrystals are separated by liquid-like grain boundary regions which widen as the vortex system temperature increases. The NCRI of the corresponding zero-temperature bosonic systems can then be numerically evaluated by solving the equations of superfluid hydrodynamics in the channels near the grain boundaries. We find that the NCRI increases very abruptly as the liquid regions in the vortex system (equivalently, superfluid regions in the bosonic system) form a connected, system-spannig structure with one or more closed loops. The implications of these results for experimentally observed supersolid phenomena are discussed.