On the interpretation of Lorentz and holographic interference images of superconducting fluxons: the influence of the specimen thickness

The change in the topography of the magnetic field associated to a superconducting fluxon due to the finite specimen thickness and its influence on the simulation of Lorentz and holographic interference images are presented and compared to the previous results obtained by using bulk models. Substantial differences between the two cases are demonstrated. These are due to the broadening of the held at the specimen surfaces, whereas the bending of the field lines within the specimen can be overlooked. It is also shown that the range of validity of one-dimensional modelling is too restricted to be practically useful when thickness effects are considered. Finally, the influence of the perturbed reference wave in the holographic interference images is investigated, showing that this effect, in addition to that due to thickness, should be taken into account for a correct interpretation of the experimental data. (C) 1999 Elsevier Science B.V. All rights reserved.