Supersolid behavior in confined geometry

TL;DR

This study investigates supersolid behavior in confined helium-4 using torsional oscillator and heat capacity measurements, finding significantly lower non-classical rotational inertia than previous reports, with results consistent with bulk samples.

Contribution

It provides new experimental data on supersolid properties of helium-4 in confined geometries, challenging earlier higher NCRI findings and showing consistency with bulk behavior.

Findings

NCRI of 0.9% observed, lower than previous reports

Heat capacity peak matches bulk solid helium-4

Results suggest supersolid behavior persists in confinement

Abstract

We have carried out torsional oscillator (TO) and heat capacity (HC) measurements on solid 4He samples grown within a geometry which restricts the helium to thin (150 um) cylindrical discs. In contrast to previously reported values from Rittner and Reppy of 20% non-classical rotational inertia (NCRI) for similar confining dimensions, 0.9% NCRI (consistent with that found in bulk samples and samples imbedded in porous media) was observed in our TO cell. In this confined geometry the heat capacity peak is consistent with that found in bulk solid samples of high crystalline quality.