  The dispersion of any given material is crucial for its charge carriers'
dynamics. For all-electronic, gate-defined cavities in gapped bilayer graphene,
we developed a trajectory-tracing algorithm aware of the material's electronic
properties and details of the confinement. We show how the anisotropic
dispersion of bilayer graphene induces chaotic and regular dynamics depending
on the gate voltage, despite the high symmetry of the circular cavity. Our
results demonstrate the emergence of non-standard fermion optics solely due to
anisotropic material characteristics.
