Regensburg 1998 – scientific programme
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TT: Tiefe Temperaturen
TT 21: Postersitzung III: Spin-Peierls-Systeme, Metall-Isolator-Übergang, Lokalisierung; SL: Theorie; Quantenflüssigkeiten und -kristalle; Amorphe Materialien, Tunnelsysteme; Borcarbide, Fullerene, konventionelle SL; SL dünner Filme; Experimentiertechniken
TT 21.51: Poster
Thursday, March 26, 1998, 15:00–18:30, D
Statics and Dynamics of Elementary Steps on c-Facets in 4He Crystals — •A. Husmann1, A.V. Babkin1, A.Ya. Parshin2, V.G. Tsepelin1, and G. Tvalashvili3 — 1Helsinki University of Technology — 2P.L. Kapitza Institute for Physical Problems — 3Universität Bayreuth
Spiral growth of facets in helium crystals can be used as a tool to probe statics and dynamics of elementary steps. Due to the large spatial separation of neighbouring steps in a rotating spiral, the step-step interaction is small and properties of individual steps determine the growth of the facet. We have studied the evolution of c-facets in 4He crystals at temperatures below 100 mK. Different amounts of 3He (between 0.1 and 100 ppm) were added to the liquid 4He phase. Interactions between the 3He impurities and the elementary steps on the interface play a dominant role in the growth dynamics of the 4He crystals below the Fermi temperature TF of the dilute 3He gas. However, at intermediate temperatures scattering from phonons in the bulk governs the motion of the steps. Our measurements also allow us to calculate the free energy and average profile of an elementary step which are found in agreement with the ”weak coupling" concept.