Classical rotational inertia of solid helium 4

TL;DR

This paper investigates whether the observed reduced rotational inertia in solid helium-4 is due to superfluidity or wall slippage, providing calculations that support the slippage explanation as a plausible alternative.

Contribution

The authors present a detailed calculation showing that grain boundary premelting and viscous slippage can explain the reduced inertia, challenging the superfluidity interpretation.

Findings

Slippage can account for the observed inertia reduction.

Calculated film thickness and viscous drag support the slippage hypothesis.

Superfluidity is not necessarily required to explain the observations.

Abstract

The observation of reduced rotational inertia in a cell containing solid helium 4 has been interpreted as evidence for superfluidity of the solid. An alternative explanation is slippage of the solid at the container wall due to grain boundary premelting between the solid and dense adsorbed layers at the container wall. We calculate the range of film thickness and the viscous drag, and find that the slippage can account for the observations.