FEATURES OF FLAT SUPERCONDUCTORS MAGNETIZATION IN PERPENDICULAR FIELD

Magnetic flux behavior in flat type II superconductors in external per pendicular field has some peculiarities determined only by their shape . The most important one is a barrier-like initial flux penetration in to such thin samples with rectangular cross-sections. Another one is a rather peculiar flux penetration pattern if the sample is not a circu lar disk. These features, showing inapplicability of the ellipsoidal a pproximation to real samples, are demonstrated by means of direct magn eto-optical observations.