  Interest in ZrTe5 has been reinvigorated in recent years owing to its
potential for hosting versatile topological electronic states and intriguing
experimental discoveries. However, the mechanism of many of its unusual
transport behaviors remains controversial, for example, the characteristic peak
in the temperature-dependent resistivity and the anomalous Hall effect. Here,
through employing a clean dry-transfer fabrication method under inert
environment, we successfully obtain high-quality ZrTe5 thin devices that
exhibit clear dual-gate tunability and ambipolar field effects. Such devices
allow us to systematically study the resistance peak as well as the Hall effect
at various doping densities and temperatures, revealing the contribution from
electron-hole asymmetry and multiple-carrier transport. By comparing with
theoretical calculations, we suggest a simplified semiclassical two-band model
to explain the experimental observations. Our work helps to resolve the
long-standing puzzles on ZrTe5 and could potentially pave the way for realizing
novel topological states in the two-dimensional limit.
