A non-superfluid origin of the non-classical rotational inertia in a bulk sample of solid 4He

TL;DR

This study investigates how disorder affects the non-classical rotational inertia in solid helium-4, revealing that the observed effects are likely due to non-superfluid mechanisms rather than supersolidity.

Contribution

It provides evidence that the non-classical rotational inertia in solid helium-4 has a non-superfluid origin, challenging the supersolid hypothesis.

Findings

NCRI increases with disorder

Period changes occur mainly at higher temperatures

Low-temperature period remains relatively unchanged

Abstract

The torsional oscillator experiments described here examine the effect of disorder on the non-classical moment of inertia (NCRI) of a solid 4He sample. The NCRI increases with increasing disorder, but the period changes responsible for this increase occur primarily at higher temperatures, while at the lowest temperature the oscillator period remains relatively unaffected. This result is contrary to expectations based on a supersolid scenario and points to a non-superfluid origin for the NCRI.