Design of a scanning Josephson junction microscope for submicron-resolution magnetic imaging

We describe a magnetic field scanning instrument designed to extend the spa tial resolution of scanning superconducting quantum interference device mic roscopy into the submicron regime. This instrument, the scanning Josephson junction microscope, scans a single Josephson junction across the surface o f a sample, detecting the local magnetic field by the modulation of the jun ction critical current. By using a submicron junction and a scanning tunnel ing microscope feedback system to maintain close proximity to the surface, magnetic field sensitivity of 10 mu G with a spatial resolution of 0.3 mu m should be attainable, opening up new opportunities for imaging vortex conf igurations and core structure in superconductors and magnetic domains in ma gnetic materials. (C) 1999 American Institute of Physics. [S0034-6748(99)00 311-1].