DHVA STUDIES OF NBSE2 USING THE TORQUE METHOD

We present torque measurements on 2H-NbSe2 in strong magnetic fields u p to 27 T and at temperatures between 0.4 K and 4.2 K. The angular dep endence of the de Haas-van Alphen (dHvA) frequency and of the effectiv e mass has been studied for angles between 5 degrees and 89 degrees yi elding a larger lateral extent and a smaller thickness of the well-kno wn pancake Fermi surface compared to previous estimations. Two so-call ed spin zeros were detected at the angles Theta = 43 degrees and Theta = 14.5 degrees. Assuming the same angular dependence for the effectiv e mass as for the dHvA frequency we give an estimation of the effectiv e g-factor for the case that g is isotropic to g = 1.2 +/- 0.1. Measur ements below the critical field Bet show first of all a stronger dampi ng of the oscillations compared to the normal state and, depending on the field sweep rate, a slight frequency shift.