COMPUTER-SIMULATIONS OF ELECTRON HOLOGRAPHIC CONTOUR MAPS OF SUPERCONDUCTING FLUX LINES

The problem of the observation of superconducting flux lines by means of electron holography techniques in transmission electron microscopy is considered. Using a simple model for a single flux line, two experimental set-ups are investigated, with the flux line lying parallel or perpendicular, respectively, to the electron beam. In the first case, it is demonstrated that the phase shift is below the detectability limits of even the most advanced holographic phase-amplification methods. In the second case, the model, and its implementation, allows the interpretation of recent experimental results concerning the holographic interferometric mapping of the exit field of flux lines in bulk specimens. Finally, the effect of the closure field on the contour maps image of a flux line in a thin specimen is investigated.