Evidence for Weyl fermions in a heavy fermion semimetal YbPtBi*

Materials with non-trivial band topology have been extensively studied in weakly correlated electron systems. Consequently, it is of great interest to test the existence of Weyl fermions when the electronic correlations are strong. Here, we report electronic structure calculations, ARPES, magneto-transport and calorimetric measurements of the canonical heavy fermion semimetal YbPtBi[1], we find triply degenerate points existed in band structure, which split into pairs of Weyl nodes under applying magnetic field. At high temperatures, the chiral anomaly effect is detected in the magneto-transport measurements, which becomes negligible when the electronic correlations become stronger at lower temperatures. However, the topological Hall effect and the temperature dependence of specific heat still demonstrate the existence of Weyl nodes. These results suggest that YbPtBi is a Weyl heavy fermion semimetal, where the bands hosting Weyl nodes are strongly renormalized at low temperatures due to the Kondo effect. Our findings provide a suitable platform to explore the interplay between topology and strong electronic correlations.
[1] C. Y. Guo, F. Wu, Z. Z. Wu, M. Smidman, C. Cao, A. Bostwick, C. Jozwiak, E. Rotenberg, Y. Liu, F. Steglich & H. Q. Yuan*. Evidence for Weyl fermions in a canonical heavy fermion semimetal YbPtBi. Nat. Comms. 9, 4622 (2018).