Interference pattern of a coherent electron beam by localized leakage magnetic field

We report on the origin of interference patterns at the edge of nanometer-s cale Co protrusions observed by low-energy electron point source (LEEPS) mi croscopy. We find evidence that those interference patterns are due to the phase shift of a coherent electron beam by a localized magnetic field. Typi cal interference patterns have an apparent size of 10-100 nm and a star-lik e shape, which are dependent on the sharpness of the Co protrusion. After p reparing a ferromagnetic nanoparticle in a saturation remanent state by app lying a strong magnetic field, we observed the deflection of the interferen ce pattern. This phenomenon is consistent with the theoretical prediction b ased on a magnetostatic model. The capability of mapping the local magnetic field suggests that LEEPS microscopy is potentially applicable as an imagi ng tool of magnetic field with nanometer-scale resolution. (C) 2001 America n Institute of Physics.