Fig. 1.

Fermi-arc-induced Weyl orbit oscillations. a The calculated Weyl points and a possible Fermi arc in the k _z = 0 plane of WTe₂ ^6,13. The Fermi arcs are mainly along Y direction. b Schematic of a Fermi-arc-induced Weyl orbit in a thin WTe₂ nanoribbon, in which the magnetic field is along the z-axis (or c-) axis. This schematic is similar to that proposed by Potter et al.¹⁹. This Weyl orbit is formed by connecting two bulk paths along the z-direction through the zeroth chiral bulk Landau level (LL) and two Fermi arcs in the momentum space, on both the top and bottom surfaces. The trajectory of the Weyl orbit in real space is in the xz plane, and the Weyl orbit is plotted in a combination of real space and momentum space. The Weyl points with opposite chirality are labeled as + (blue) and – (purple). c Conventional quantum oscillation orbit. d MR of the b-axis ribbon (19.4 nm thick) at different temperatures with B//c. Inset shows a metal–insulator transition under a magnetic field of 14 T. e The pronounced SdH oscillations are observed at different temperatures in the plots of d² R/dB ² vs. B. f Comparison of FFT of the data of d² R/dB ² vs. B obtained from bulk WTe₂ and b-axis ribbon (T = 2 K). The FFT data obtained from d² R/dB ² vs. B for B > 8.0 T shows an extra frequency of 78 T. g The FFT spectra of b-axis ribbon at different temperatures