Topological Hysteresis, Structure and Nucleation of the Intermediate State in Type-I Superconductors

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Non-technical abstractThe superconducting intermediate state is formed in elemental (type-I) superconductors as acomplex pattern of normal and superconducting regions. Newly developedexperimental techniques may lead to a substantial revision of our currentunderstanding of this state. These techniques allow one to observe localmagnetic fields of the intermediate state in real time and to measure themwith extreemly high sensitivity. This research has connections to importantquestions of pattern formation in complex mathematical, geophysical,chemical and biological systems and even to the formation of galaxies. Theproject carries significant educational impact. Students of all levels willwork on the project, each performing specific set of measurements. Someexperiments will be part of the advanced solid-state physics laboratory. Theproject involves active domestic and international collaborations with theleading experts in the field, including those who initiated related studiesdecades ago. A workshop on pattern formation in type-I superconductors isplanned at the end of the research term.Technical abstractThis individual investigator award will support comprehensive studies of theintermediate state in type-I superconductors. Unique experimentaltechniques, such as magneto-optical visualization of magnetic fields andpico-emu sensitive tunnel-diode susceptometry, combined with conventionalmethods, will be employed to understand the intermediate state in a broadercontext of pattern formation in highly nonlinear systems. The study oftopological hysteresis and complex shape effects may lead to theidentification of unusual thermodynamically equilibrium states and,ultimately, to substantial revisions of our current understanding of type-Isuperconductivity. The ability to continuously tune the system across abroad range of topologies using both temperature and magnetic field makestype-I superconductivity an ideal arena in which to study general questionsof pattern formation in nonlinear systems. Connections to biological,chemical and astrophysical systems will be studied as part of this project.The project carries significant educational impact. Students of all levelswill work on the project, each performing specific set of measurements. Someexperiments will be part of the advanced solid-state physics lab. Theproject involves active domestic and international collaborations with theleading experts in the field, including those who initiated related studiesdecades ago. A workshop on pattern formation in type-I superconductors isplanned at the end of the research term.