QUANTUM OSCILLATIONS IN THE VORTEX STATE OF NBSE2

Quantum oscillations of the magnetization, the de Haas-van Alphen effe ct, have been studied in the vortex state of the layer compound, NbSe2 . On Passing from the normal to the superconducting state, we find a s mall field dependent increase in the quasiparticle scattering rate. Pa rticularly striking, however, is that the quantum oscillations persist to values of magnetic field as low as approximately 0.25 B(c2) and te mperatures of 0.003T(C). These results, are discussed in terms of rece nt theories of the dHvA effect in the vortex state.