Quantum Hall signature of Weyl orbits in dual-gated Dirac semimetal film

Recent prediction and observation of quantum Hall effect in three-dimensional topological semimetals [1-3] have attracted growing attention on the novel transport phenomena exerted by an exotic orbit so-called Weyl orbit. The Weyl orbit interconnects two spatially-separated surface Fermi-arc states via bulk Weyl nodes. While previous reports have focused on the subtle bulk thickness dependence of Weyl orbits [2], experimental evidence of their unique spatial distribution with electrons looping between two opposite surfaces has been missing. In this talk, we report Weyl-orbit-induced intrinsic coupling between top and bottom surface states in the quantum Hall regime of a dual-gated Dirac semimetal film. In particular, the doubly-degenerate quantum Hall states exhibit simultaneous modulation by top and/or bottom electric fields. The characteristic plateau transition patterns observed in electric and magnetic field scans directly evidence that the quantized states are not based on two independently localized conventional surface orbits, but rather based on a pair of Weyl orbits formed across the two opposite surfaces.
[1] C. M. Wang et al. Phys. Rev. Lett. 119, 136806 (2017)
[2] C. Zhang et al. Nature 565, 331-336 (2019)
[3] S. Nishihaya et al. Nat. Commun. 10, 2564 (2019)