  The recent experimental discovery of the zero-field fractional Chern
insulator (FCI) in twisted $\mathrm{MoTe_2}$ moir\'e superlattices has sparked
immense interest in this exotic topological quantum state. The FCI has also
been observed in previous experiments in magic angle twisted bilayer graphene
(TBG) under a finite magnetic field of about 5 Tesla. Generally, the
stabilization of FCI requires fine-tuning the topological band to satisfy
certain conditions. It would still be helpful to have an intuitive picture to
understand the different behaviors in twisted $\mathrm{MoTe_2}$ and TBG. Here,
we compare them through the lens of emergent gauge fields. In TBG, the system
can be mapped to two Dirac fermions coupled to emergent gauge fields with
opposite signs. In contrast, the twisted $\mathrm{MoTe_2}$ reduces to a hole
with parabolic dispersion coupled to an emergent gauge field. This contrasting
gauge structure provides a new perspective on the observed difference: the
zero-field FCI is stable in $\mathrm{MoTe_2}$ but absent in TBG. Based on this
understanding, we will explore potential strategies for stabilizing FCI in both
moir\'e superlattices.
