This collaborative experimental condensed matter physics project explores the fundamental physics of static and dynamic phases of spatially modulated states in superconductors. The focus is on two important problems in this area: the role of strong magnetic fields on quantum tunneling phenomena, and the dynamic behavior of magnetic field-induced defects in superconductors in artificially constrained geometries. One emphasis of the work is on direct spatial imaging of modulated superconducting states using scanning Hall probe microscopy, a technique that allows non-invasive mapping of the local magnetic field above superconducting and magnetic structures. This project is a collaborative effort involving two investigators with complementary expertise in magnetism and superconductivity. A central part of the project is the training of both graduate and undergraduate students in physics and materials research techniques. The skills they will develop will position them to contribute to the nation's scientific base in a variety of future career paths. %%% This project will investigate two important problems in the field of superconductivity. A key technique used throughout the project is that of scanning Hall probe microscopy, which allows non-invasive mapping of the local magnetic field above superconducting and magnetic structures. In the first study, the role of strong magnetic fields on the tunneling of electrons between two superconductors will be investigated. The physics of this tunneling in large fields is currently only partly understood. The Hall microscope will be particularly a powerful tool in this study, as it allows for the direct imaging of the flowing supercurrents. In the second area of investigation, the Hall microscope will be used to image the static and dynamic behavior of vortices in superconductors that have been structured using micro- and nano-lithographic techniques. One such example to be studied is a novel "vortex ratchet", in which vortices can be moved in precisely controlled steps. This ratchet may have possible applications in high-precision metrology. A central part of the project is the training of both graduate and undergraduate students in physics and materials research techniques. The skills they will develop will position them to contribute to the nation's scientific base in a variety of future career paths.
