Approaching three-dimensional quantum Hall effect in bulk HfT e5

We report the electronic transport features of HfT e₅ under external magnetic field. We observe a series of plateaus in Hall resistance ρ_{x y} as magnetic field increases until it reaches the quantum limit at 1-2 Tesla. At the plateau regions, the longitudinal resistance ρ_{x x} exhibits local minima. Although ρ_{x x} is still nonzero, its value becomes much smaller than ρ_{x y} at the last few plateaus. By mapping the Fermi surface via measuring the Shubonikov-de Haas oscillation, we find that the strength of Hall plateau is proportional to the Fermi wavelength, suggesting that its formation may be attributed to the gap opening from the interaction driven Fermi surface instability. By comparing the bulk band structures of ZrT e₅ and HfT e₅ , we find that there exists an extra pocket near the Fermi level of HfT e₅ , which may lead to the finite but nonzero longitudinal conductance.