Torsional oscillators and the entropy dilemma of putative supersolid He-4

Abstract

Solid He-4 is viewed as a nearly perfect Debye solid. Yet, recent calorimetry measurements by the PSU group (J. Low Temp. Phys. 138, 853 (2005) and Nature 449, 1025 (2007)) indicate that at low temperatures the specific heat has both cubic and linear contributions. These features appear in the same temperature range where measurements of the torsional oscillator period suggest a supersolid transition. We analyze the specific heat and compare the measured with the estimated entropy for a proposed supersolid transition with 1% superfluid fraction and find that the observed entropy is too small. We suggest that the low-temperature linear term in the specific heat is due to a glassy state that develops at low temperatures and is caused by a distribution of tunneling systems in the crystal. We propose that dislocation related defects produce those tunneling systems. Further, we argue that the reported putative mass decoupling, that means an increase in the oscillator frequency, is consistent with a glass-like transition. The glass scenario offers an alternative interpretation of the torsional oscillator experiments in contrast to the supersolid scenario of nonclassical rotational inertia.

Presented at LT-25, Amsterdam 2008

References in corpus (12)

• Low Temperature Shear Modulus Changes in Solid 4-He and Connection to Supersolidity
• Luttinger Liquid in the Core of Screw Dislocation in Helium-4
• Disorder and the Supersolid State of Solid ${}^4$He
• Oscillation Frequency Dependence of Non-Classical Rotation Inertia of Solid ${}^4$He
• Observation of non-classical rotational inertia in bulk solid 4He
• On the origin of the decrease in the torsional oscillator period of solid He4
• Entropy of solid He4: the possible role of a dislocation glass
• Probing the Upper Limit of Nonclassical Rotational Inertia
• Dislocation Glasses: Aging during Relaxation and Coarsening
• Bose-Einstein Condensate in Solid Helium
• Absence of low temperature anomaly in the Debye-Waller factor of solid He-4
• Dissipation peak as an indicator of sample inhomogeneity in solid ${}^4$He oscillator experiments

Cited by in corpus (4)

• The glassy response of solid He-4 to torsional oscillations
• A glass anomaly in the shear modulus of solid ${}^4$He
• Effects of ${}^3$He Impurity on Solid ${}^4$He Studied by Compound Torsional Oscillator
• Shear modulus in viscoelastic solid ${}^4$He