Two types of three-dimensional quantum Hall effects in multilayer WTe2

Interplay between topological surface states and bulk states gives rise to diverse exotic transport phenomena in topological materials. The recently proposed Weyl orbit in topological semimetals in the presence of magnetic field is a remarkable example. This novel closed magnetic orbit consists of Fermi arcs on two spatially separated sample surfaces which are connected by the bulk chiral zero mode, which can contribute to transport. Here we report Shubnikov--de Haas oscillation and its evolution into quantum Hall effect (QHE) in multilayered type-II Weyl semimetal $\mathrm{W}{\mathrm{Te}}_{2}$. We observe both the three-dimensional (3D) QHE from bulk states by parallel stacking of confined two-dimensional layers in the low magnetic field region and the 3D QHE in the quantized surface transport due to Weyl orbits in the high magnetic field region. Our study of the two types of QHEs controlled by magnetic field and our demonstration of the crossover between quantized bulk and surface transport provide an essential platform for the future quantized transport studies in topological semimetals.