  The intrinsic magnetic order, large topological-magnetic gap and rich
topological phases make MnBi2Te4 a wonderful platform to study exotic
topological quantum states such as axion insulator and Chern insulator. To
realize and manipulate these topological phases in a MnBi2Te4 thin film,
precise manipulation of the electric field across the film is essential, which
requires a dual-gate structure. In this work, we achieve dual-gate tuning of
MnBi2Te4 thin films grown with molecular beam epitaxy on SrTiO3(111) substrates
by applying the substrate and an AlOx layer as the gate dielectrics of bottom
and top gates, respectively. Under magnetic field of 9T and temperature of 20
mK, the Hall and longitudinal resistivities of the films show inversed
gate-voltage dependence, for both top- and bottom-gates, signifying the
existence of the dissipationless edge state contributed by Chern insulator
phase in the ferromagnetic configuration. The maximum of the Hall resistivity
only reaches 0.8 h/e2, even with dual-gate tuning, probably due to the high
density of bulk carriers introduced by secondary phases. In the
antiferromagnetic state under zero magnetic field, the films show normal
insulator behavior. The dual-gated MnBi2Te4 thin films lay the foundation for
developing devices based on electrically tunable topological quantum states.
