Anomalous Shubnikov-de Haas effect in Topological Semimetal YPtBi

Theory predicts the RPtBi (R=rare earth) half-Heusler compounds are topological semimetals, and recent experimental observations of the large anomalous Hall effect and the chiral anomaly in GdPtBi were both attributed to the non-trivial Berry phase. However, there has not been any direct measurements of the Berry phase in the RPtBi system. Here we study the angle-dependent Shubnikov-de Haas (SdH) effect arising from the spin-split bulk Fermi surface of a prototypical half-Heusler compound YPtBi. We will describe observations of an anomalous angle dependence of SdH oscillations, investigating the angle-dependent cyclotron mass, scattering rate, and Berry phase of two beating oscillations from the spin-split Fermi surface. This unprecedentedly anomalous SdH effect sheds light on the topological nature of the half-Heusler family of compounds as well as offers an excellent model system for the SdH effect influenced by the strong spin-orbit coupling.