Instability-driven formation of domains in the intermediate state of type-I superconductorsV. Jeudy and C. Gourdon
Institut des Nanosciences de Paris, Université Pierre et Marie Curie-Paris 6 Université Denis Diderot-Paris 7, CNRS, UMR 7588, Campus Boucicaut 140 rue de Lourmel, 75015 Paris, France
received 28 March 2006; accepted in final form 7 June 2006
published online 28 June 2006
The formation of normal-state domains in type-I superconducting indium films is investigated using the high-resolution magneto-optical imaging technique. The observed patterns consist of coexisting circular and lamellar normal-phase domains surrounded by the superconducting phase. The distribution of domain surface areas is found to exhibit a threshold, above which only the lamellar shape is observed. We show that this threshold coincides with the predicted critical surface area for the elongation instability of the circular shape. The partition of the normal phase into circular and lamellar domains is determined by the combined effects of the elongation instability and the penetration of magnetic flux by bursts at the early stage of pattern formation. It is not governed by mutual interactions between domains, as usually assumed for self-organized systems.
74.25.Ha - Magnetic properties.
05.65.+b - Self-organized systems.
75.70.Kw - Domain structure (including magnetic bubbles).
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