Large Magnetoresistance and Quantum Oscillations in Sn0.05Pb0.95Te.

We have synthesized high-quality single crystals of SnxPb1-xTe 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 ∼310% atH= 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,fα∼ 57 T. However, an additional frequency,fβ∼ 69 T, appears as the angle between the field direction and the normal to the sample surface (θ) is increased. Bothfαandfβexhibitθ-dependence;fαdecreases whereasfβincreases gradually with increasingθ. The presence of two frequencies in Sn0.05Pb0.95Te indicates that there exist two Fermi surface pockets (αandβpockets). We have constructed the Landau-level fan plot and determined the Berry phase (δ) for theαpocket to beδ∼ 0.1. Thisδvalue is very close to the expected value of 0 for a topologically trivial system.