Untersuchung von Semifluxonen in langen Josephson 0-pi-Kontakten

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Due to the recent progress in fabrication technology, several types of p-junctions, e.g. based on anisotropic cuprate superconductors with d-wave order parameter symmetry or on superconductor-ferromagnet structures, are available now for experimental investigations. In a long Josephson junction containing 0 and p parts comparable by length with the Josephson penetration depth lJ, at the point where 0 and p facets join, fractional vortices are spontaneously created at certain conditions. Such fractional vortices usually carry only one half of a magnetic flux quantum and therefore are called semifluxons. Within this project we focus on the experimental investigation of the behaviour of fractional vortices in 0-p-LJJs. Semifluxons are very different from fluxons in a way they form a ground state, how they move, how they interact with each other and with fluxons. Semifluxons can result in half-integer quantization of observable parameters and have many other interesting features. This investigation is intended to improve the understanding of fractional quantization in superconductors, to study the behavior of fractional flux quanta and to suggest and try new ideas for Josephson electronics in the classical or the quantum regime.