Magnetic oscillations in the heavy-fermion superconductor UBe13

We present measurements of the magnetic torque acting upon a single crystal of UBe13, measurements made with a capacitive magnetometer. We observe pronounced magnetic oscillations in the torque resulting from the de Haas--van Alphen effect. A conventional analysis reveals that these oscillations result from ''light fermions'' with an effective mass m*=0.017me (me is the bare electron mass). The Fermi surface associated with these light quasiparticles is anisotropic. We present arguments that these oscillations represent an intrinsic phenomenon and compare our results with those of other groups