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Search for Dislocation Free Helium 4 Crystals

Authors
  • Souris, F.1
  • Fefferman, A. D.1, 2
  • Haziot, A.1, 3
  • Garroum, N.1
  • Beamish, J. R.1, 4
  • Balibar, S.1
  • 1 Laboratoire de Physique Statistique de l’École Normale Supérieure associé au CNRS et aux Universités P.M. Curie et D. Diderot, 24 rue Lhomond, Paris Cedex 05, 75231, France , Paris Cedex 05 (France)
  • 2 Université Grenoble Alpes, CNRS Institut NÉEL, Grenoble Cedex 9, 38042, France , Grenoble Cedex 9 (France)
  • 3 Pennsylvania State University, Department of Physics, University Park, PA, 16802, USA , University Park (United States)
  • 4 University of Alberta, Department of Physics, Edmonton, AB, T6G 2E1, Canada , Edmonton (Canada)
Type
Published Article
Journal
Journal of Low Temperature Physics
Publisher
Springer US
Publication Date
Dec 02, 2014
Volume
178
Issue
3-4
Pages
149–161
Identifiers
DOI: 10.1007/s10909-014-1251-0
Source
Springer Nature
Keywords
License
Green

Abstract

The giant plasticity of 4\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$^4$$\end{document}He crystals has been explained as a consequence of the large mobility of their dislocations. Thus, the mechanical properties of dislocation free crystals should be quite different from those of usual ones. In 1996–1998, Ruutu et al. published crystal growth studies showing that, in their helium 4 crystals, the density of screw dislocations along the c-axis was less than 100 per cm2\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$^2$$\end{document}, sometimes zero. We have grown helium 4 crystals using similar growth speeds and temperatures, and extracted their dislocation density from their mechanical properties. We found dislocation densities that are in the range of 104\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$^4$$\end{document}–106\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$^6$$\end{document} per cm2\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$^2$$\end{document}, that is several orders of magnitude larger than Ruutu et al. Our tentative interpretation of this apparent contradiction is that the two types of measurements are somewhat indirect and concern different types of dislocations. As for the dislocation nucleation mechanism, it remains to be understood.

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