Tunnelling defect nanoclusters in hcp 4He crystals: alternative to supersolidity

TL;DR

This paper proposes a model where resonant tunnelling defect clusters explain low-temperature anomalies in hcp 4He crystals, offering an alternative to the supersolidity hypothesis by linking observed phenomena to internal Josephson effects.

Contribution

It introduces a simple, defect-based tunnelling model that accounts for various low-temperature anomalies in helium crystals, providing a new perspective beyond supersolidity.

Findings

Quantitative agreement with experimental data

Explains mass decoupling via internal Josephson effect

Accounts for shear modulus and heat capacity anomalies

Abstract

A simple model based on the concept of resonant tunnelling clusters of lattice defects is used to explain the low temperature anomalies of hcp 4He crystals (mass decoupling from a torsional oscillator, shear modulus anomaly, dissipation peaks, heat capacity peak). Mass decoupling is a result of an internal Josephson effect: mass supercurrent inside phase coherent tunnelling clusters. Quantitative results are in reasonable agreement with experiments.