  The realization of chiral Majorana modes is a challenging task. We aim to
comprehend the phase diagrams and parameter control capabilities of the actual
devices used in the chiral Majorana search. Beyond the well-known minimal
models, we develop a numerical simulation scheme using a self-consistent
Schrodinger-Poisson approach to study, as an example, the MnBi2Te4 thin film
coupled to an s-wave superconductor. We show that both the superconducting
proximity effect and the tunability of the chemical potential for the
topological surface states are significantly influenced by the gate-induced
electrostatic potential. This complicates the implementation in experiments,
and the actual topological region will be narrowed in stark contrast to those
predicted in the previous minimal models. Nevertheless, we demonstrate that the
chiral Majorana mode still exists in a wide range of experimental parameters
with practical tunability.
