A glassy contribution to the heat capacity of hcp ${}^4$He solids

Abstract

We model the low-temperature specific heat of solid ${}^4$He in the hexagonal closed packed structure by invoking two-level tunneling states in addition to the usual phonon contribution of a Debye crystal for temperatures far below the Debye temperature, $T<{\Theta }_D/50$. By introducing a cutoff energy in the two-level tunneling density of states, we can describe the excess specific heat observed in solid hcp ${}^4$He, as well as the low-temperature linear term in the specific heat. Agreement is found with recent measurements of the temperature behavior of both specific heat and pressure. These results suggest the presence of a very small fraction, at the parts-per-million (ppm) level, of two-level tunneling systems in solid ${}^4$He, irrespective of the existence of supersolidity.

arXiv comment11 pages, 4 figures

References in corpus (21)

• Low Temperature Shear Modulus Changes in Solid 4-He and Connection to Supersolidity
• Disorder and the Supersolid State of Solid ${}^4$He
• Oscillation Frequency Dependence of Non-Classical Rotation Inertia of Solid ${}^4$He
• Observation of Unusual Mass Transport in Solid hcp 4He
• Pressure-driven flow of solid helium
• Evidence for a Superglass State in Solid 4He
• Observation of non-classical rotational inertia in bulk solid 4He
• Supersolid Helium at High Pressure
• Annealing Effect for Supersolid Fraction in ${}^4$He
• Nonclassical Rotational Inertia in Single Crystal Helium
• On the origin of the decrease in the torsional oscillator period of solid He4
• Freezing and pressure-driven flow of solid helium in Vycor
• Intrinsic and dislocation induced elastic behavior of solid helium
• Entropy of solid He4: the possible role of a dislocation glass
• Vortex Fluid State below an Onset Temperature T_0 of Solid 4He
• Heat capacity peak in solid 4He: Effects of disorder and 3He impurities
• Absence of low temperature anomaly in the Debye-Waller factor of solid He-4
• Melting curve of ${}^4$He: no sign of the supersolid transition down to 10 mK
• Absence of low temperature anomaly on the melting curve of ${}^4$He
• Supersolid behavior in confined geometry
• Non-Classical Response from Quench-Cooled Solid Helium Confined in Porous Gold

Cited by in corpus (8)

• Mass flow through solid 4He induced by the fountain effect
• A glass anomaly in the shear modulus of solid ${}^4$He
• The glassy response of double torsion oscillators in solid Helium-4
• A search for disordered (glassy) phase in solid 3He deformed in situ
• Shear modulus in viscoelastic solid ${}^4$He
• Defects and glassy dynamics in solid He-4: Perspectives and current status
• Saga of Superfluid Solids
• The role of glass dynamics in the anomaly of the dielectric function of solid helium