Shubnikov-de Haas oscillations in Pb_1-xSn_xTe epitaxial films

Topological crystalline insulators (TCIs) are a class of materials prized in recent years for their ability to form symmetry-protected massless surface states. SnTe is a TCI while PbTe is a trivial insulator, but Pb1-xSnxTe shows a topological phase transition at X~0.4. Higher Pb concentrations yield a trivial insulator while lower concentrations yield a TCI. Characterizing the surface states at Sn rich side of the transition remains elusive due to parasitic transport from. We grew high quality Pb1-xSnxTe heterostructures in a chalcogenide molecular beam epitaxy system. XRD measurements confirm single crystal thin films grown epitaxially on BaF2 (111) substrates. High field magnetoresistance measurements were carried out at various temperatures (10mK-700mK) and angles. We analyzed Shubnikov de-Haas (SdH) oscillations in samples with various Sn concentrations at various temperatures and field angles. The summed frequencies contained in the SdH oscillations elucidate the nature of topological surface states.