Dislocation networks in helium-4 crystals

Abstract

The mechanical behavior of crystals is dominated by dislocation networks, their structure and their interactions with impurities or thermal phonons. However, in classical crystals, networks are usually random with impurities often forming non-equilibrium clusters when their motion freezes at low temperature. Helium provides unique advantages for the study of dislocations: crystals are free of all but isotopic impurities, the concentration of these can be reduced to the ppb level, and the impurities are mobile at all temperatures and therefore remain in equilibrium with the dislocations. We have achieved a comprehensive study of the mechanical response of 4He crystals to a driving strain as a function of temperature, frequency and strain amplitude. The quality of our fits to the complete set of data strongly supports our assumption of string-like vibrating dislocations. It leads to a precise determination of the distribution of dislocation network lengths and to detailed information about the interaction between dislocations and both thermal phonons and 3He impurities. The width of the dissipation peak associated with impurity binding is larger than predicted by a simple Debye model, and much of this broadening is due to the distribution of network lengths.

accepted by Phys. Rev. B

References in corpus (4)

• Oscillation Frequency Dependence of Non-Classical Rotation Inertia of Solid ${}^4$He
• The giant plasticity of a quantum crystal
• Critical dislocation speed in helium-4 crystals
• Plastic response by dislocation glide in solid helium under dc strain rate loading

Cited by in corpus (11)

• Simulation and understanding of quantum crystals
• Quantum Plasticity and Supersolid Response in Helium-4
• Dissipative superfluid mass flux through solid 4He
• Frequency-dependent Study of Solid Helium-4 Contained in a Rigid Double-torus Torsional Oscillator
• Effect of Rotation on Elastic Moduli of Solid ${}^4$He
• Nonlinear and Hysteretic Ultrasound Propagation in Solid ${}^4$He: Dynamics of Dislocation Lines and Pinning Impurities
• Superfluid-like TO Responses in Rotating Solid Helium
• Simultaneous investigation of shear modulus and torsional resonance of solid 4He
• Dislocation Mobility and Anomalous Shear Modulus Effect in ${}^4$He Crystals
• Superfluid Field response to Edge dislocation motion
• Low frequency elastic measurements on solid ${}^4$He in Vycor using a torsional oscillator