Study of Supersolidity and Shear Modulus Anomaly of 4He in a Triple Compound Oscillator

TL;DR

This study investigates the shear modulus anomaly and potential supersolidity in solid 4He using a triple compound oscillator, concluding that observed period shifts below 200 mK are mainly due to shear modulus changes rather than supersolidity.

Contribution

The paper introduces a triple compound oscillator setup to distinguish between shear modulus effects and supersolidity in solid 4He, providing new experimental evidence.

Findings

Period shifts below 200 mK are primarily caused by shear modulus variations.

The experiment isolates shear effects from supersolid signals in torsional oscillator data.

Shear modulus changes account for the observed anomalies, not supersolidity.

Abstract

The recently discovered shear modulus anomaly in solid 4He bears a strong similarity to the phenomenon of supersolidity in solid 4He and can lead to the period shift and dissipative signals in torsional oscillator experiments that are nearly identical to the classic NCRI signals observed by Kim and Chan. In the experiments described here, we attempt to isolate the effects of these two phenomena on the resonance periods of torsion oscillators. We have constructed a triple compound oscillator with distinct normal modes. We are able to demonstrate that, for this oscillator, the period shifts observed below 200 mK have their primary origin in the temperature dependence of the shear modulus of the solid 4He sample rather than the formation of a supersolid state.