QUANTITATIVE INVESTIGATION OF THE DE-HAAS-VAN-ALPHEN EFFECT IN THE SUPERCONDUCTING STATE

The de Haas-van Alphen effect in the vortex state of the type-II super conductors 2H-NbSe2 and V3Si is studied. We discuss the experimental a nd theoretical considerations pertaining to the observation of such os cillations. Macroscopic pinning of the flux lattice cannot explain the observed attenuation of quantum oscillations in the mixed state. A cr itical comparison of our measurements with the various microscopic the oretical models describing this phenomenon is made. We show how orient ation-dependent de Haas-van Alphen data may be analyzed in a model-dep endent way to yield the variation of the superconducting gap over the Fermi surface.