Curved Facets of ⁴He Crystals

The interface between crystal and liquid ⁴He was recently studied by Babkin et al.. Surprisingly, they found that a "facet" of the crystal was not perfectly straight, but had a small curvature near the edge. One alternative to understand this phenomenon was based on dislocation half-rings (figure).

We argue that dislocation half-rings do not give rise to the curvature of facets. Instead, we suggest that the observed curvature arises from pinning of crystal steps.

Publications

• A.V. Babkin, H. Alles, P.J. Hakonen, A.Yu. Parshin, J.P. Ruutu, and J.P. Saramäki, Observation of a new surface state on ⁴He crystal interfaces, Phys. Rev. Lett. 75, 3324 (1995).
• E.V. Thuneberg: How should we understand curved facets? J. Low Temp Phys. 106, 575 (1997), preprint (pdf file, 176 kb).

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