Large magnetoresistance and quantum oscillations in Sn0.05Pb0.95Te

We have synthesized high-quality single crystals of Sn x Pb1-x Te and carried out detailed studies of the magnetotransport properties of one of the samples, Sn0.05Pb0.95Te. Longitudinal magnetoresistance increases almost linearly with increasing applied field (H) and reaches similar to 310% at H = 13 T. At higher fields, both longitudinal and Hall resistance show clear Shubnikov de Haas oscillations. The oscillations are smooth and periodic, and there exists only one frequency, f ( alpha ) similar to 57 T. However, an additional frequency, f ( beta )similar to 69 T, appears as the angle between the field direction and the normal to the sample surface (theta) is increased. Both f ( alpha ) and f ( beta ) exhibit theta-dependence; f ( alpha ) decreases whereas f ( beta ) increases gradually with increasing theta. The presence of two frequencies in Sn0.05Pb0.95Te indicates that there exist two Fermi surface pockets (alpha and beta pockets). We have constructed the Landau-level fan plot and determined the Berry phase (delta) for the alpha pocket to be delta similar to 0.1. This delta value is very close to the expected value of 0 for a topologically trivial system.