QUANTUM OSCILLATIONS AND THE FERMI-SURFACE OF LUB12

To examine the Fermi surface of LuB12, measurements of the de Haas-van Alphen (dHvA) effect were made at temperatures between 0.35 and 2 K i n magnetic fields up to 12 Tesla. Oscillations in the susceptibility o ccurred above 5 Tesla in any field direction relative to the single cr ystal sample. From the Fourier transform of the data obtained, we conc lude the Fermi surface of both conduction bands to have multiple extre mal cross sections. For some of these orbits, the temperature dependen ce of the dHvA signal was investigated to determine the corresponding cyclotron mass. For a better understanding, a Full Potential Linearize d Augmented Plane Wave-(FLAPW-) band structure calculation was carried out and the shapes of the Fermi surfaces were determined. In addition , we investigated the transverse magnetoresistance as a function of th e field and the held direction. Its anisotropy, as well as the Shubnik ov-de Haas (SdH) oscillations occurring in certain geometries, are in agreement with the results of the dHvA measurements.