Intrinsic and dislocation induced elastic behavior of solid helium

Abstract

Recent experiments showed that the shear modulus of solid 4He stiffens in the same temperature range (below 200 mK) where mass decoupling and supersolidity have been inferred from torsional oscillator measurements. The two phenomena are clearly related and crystal defects, particularly dislocations, appear to be involved in both. We have studied the effects of annealing and the effects of applying large stresses on the elastic properties of solid 4He, using both acoustic resonances and direct low-frequency and low-amplitude measurements of the shear modulus. Both annealing and stressing affect the shear modulus, as expected if dislocations are responsible. However, it is the high temperature modulus which is affected; the low temperature behavior is unchanged and appears to reflect the intrinsic modulus of solid helium. We interpret this behavior in terms of dislocations which are pinned by isotopic 3He impurities at low temperatures and so have no effect on the shear modulus. At higher temperatures they become mobile and weaken the solid. Stressing the crystal at low temperatures appears to introduce new defects or additional pinning sites for the dislocation network but these effects can be reversed by heating the crystal above 500 mK. This is in contrast to dislocations produced during crystal growth, which are only annealed at temperatures close to melting.

References in corpus (15)

• Low Temperature Shear Modulus Changes in Solid 4-He and Connection to Supersolidity
• Luttinger Liquid in the Core of Screw Dislocation in Helium-4
• Superglass Phase of Helium-four
• Disorder and the Supersolid State of Solid ${}^4$He
• Oscillation Frequency Dependence of Non-Classical Rotation Inertia of Solid ${}^4$He
• Superfluidity of Grain Boundaries in Solid Helium-4
• Ring exchanges and the supersolid phase of 4He
• Pressure-driven flow of solid helium
• Observation of non-classical rotational inertia in bulk solid 4He
• 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
• The effect of 3He impurities on the nonclassical response to oscillation of solid 4He
• Thermal History of Solid 4He Under Oscillation
• Quenched Dislocation Enhanced Supersolid Ordering

Cited by in corpus (28)

• Supersolids: what and where are they ?
• Defect-induced supersolidity with soft-core bosons
• A non-superfluid origin of the non-classical rotational inertia in a bulk sample of solid 4He
• Non-linear Elastic Response in Solid Helium: critical velocity or strain
• Mass flow through solid 4He induced by the fountain effect
• Dislocation Mobility in a Quantum Crystal: the Case of Solid 4He
• A glassy contribution to the heat capacity of hcp ${}^4$He solids
• A glass anomaly in the shear modulus of solid ${}^4$He
• The elastic constants of solid 4He under pressure: a diffusion Monte Carlo study
• Dislocation induced anomalous softening of solid helium
• Zero-point Divacancy Concentration in the Shadow Wave-Function Model for Solid 4He
• Classification of a supersolid: Trial wavefunctions, Symmetry breakings and Excitation spectra
• The low temperature elastic anomalies in solid helium
• Josephson effects in one-dimensional supersolids
• Elastic constants of hcp ${}^4$He: Path-integral Monte Carlo results versus experiment
• Frequency-dependent Study of Solid Helium-4 Contained in a Rigid Double-torus Torsional Oscillator
• Plastic response by dislocation glide in solid helium under dc strain rate loading
• The Plastic Flow of Solid 4He through a Porous Membrane
• NMR Investigation of the Low Temperature Dynamics of solid 4He doped with 3He impurities
• NMR study of supersolid phases in the triangular-lattice antiferromagnet Na2BaCo(PO4)2
• Excitations of amorphous solid helium
• Shear modulus in viscoelastic solid ${}^4$He
• Effect of Rotation on Elastic Moduli of Solid ${}^4$He
• Simultaneous investigation of shear modulus and torsional resonance of solid 4He
• Dislocation Mobility and Anomalous Shear Modulus Effect in ${}^4$He Crystals
• Saga of Superfluid Solids
• Shear Modulus of an Elastic Solid under External Pressure as a function of Temperature: The case of Helium
• The role of glass dynamics in the anomaly of the dielectric function of solid helium