Dependence of dislocation damping on helium-3 concentration in helium-4 crystals

27th International Conference on Low Temperature Physics

Fefferman, A.D.^1 ; Souris, F.^1 ; Haziot, A.^1,2 ; Beamish, J.R.^1,3 ; Balibar, S.^1

Laboratoire de Physique Statistique de l'Ens, Associe Au CNRS, Universités D. Diderot et P.M. Curie, 24 rue Lhomond, Paris Cedex 05

75231, France^1

Present Address: Department of Physics, Pennsylvania State University, University Park

PA

16802, United States^2

Department of Physics, University of Alberta, Edmonton

AB

T6G 2E1, Canada^3

关键词: Damping forces;    Dislocation damping;    Dislocation mobility;    Dislocation networks;    Low temperatures;    Measurements of;    Mechanical dissipation;    Quantum tunneling;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/568/1/012003/pdf
DOI  :  10.1088/1742-6596/568/1/012003

来源: IOP

【 摘 要 】

The mechanical properties of crystals are strongly affected by dislocation mobility. Impurities can bind to dislocations and interfere with their motion, causing changes in the crystal's shear modulus and mechanical dissipation. In4He crystals, the only impurities are3He atoms, and they can move through the crystal at arbitrarily low temperatures by quantum tunneling. When dislocations in4He vibrate at speeds v 3He impurities move with the dislocations and exert a damping force B3v on them. In order to characterize4He dislocation networks and determine the3He binding energy, it is usually assumed that B3is proportional to the concentration of3He bound to the dislocations. In this preliminary report, we determine B3in a crystal with 2.32 ppm3He and compare with our previous measurements of B3in natural purity4He crystals to verify the assumption of proportionality.