REAL-TIME SCANNING HALL PROBE MICROSCOPY

We describe a low-noise scanning Hall probe microscope having unpreced ented magnetic field sensitivity (similar to 2.9x10(-8) T/root Hz at 7 7 K), high spatial resolution, (similar to 0.85 mu m),nd operating in real-time (similar to 1 frame/s) for studying flux profiles at surface s. A submicron Hall probe manufactured in a GaAs/A1GaAs two-dimensiona l electron gas (2DEG) is scanned over the sample to measure the surfac e magnetic fields using conventional scanning tunneling microscopy pos itioning techniques. Flux penetration into a high T-c YBa2Cu3O7-delta thin film has been observed in real time at 85 K with single vortex re solution. Flux is seen to enter the film in the form of vortex bundles as well as single flux quanta, Phi(0). (C) 1996 American Institute of Physics.