  Triple point fermions are elusive electronic excitations that generalize
Dirac and Weyl modes beyond the conventional high energy paradigm. Yet, finding
real materials naturally hosting these excitations at the Fermi energy has
remained challenging. Here we show that twisted bilayer graphene is a versatile
platform to realize robust triple point fermions in two dimensions. In
particular, we establish that the introduction of localized impurities lifts
one of the two degenerate Dirac cones, yielding triple point fermions at charge
neutrality. Furthermore, we show that the valley polarization is preserved for
certain impurity locations in the moire supercell for both weak and strong
impurity potentials. We finally show that in the presence of interactions, a
symmetry broken state with local magnetization can develop out of the triple
point bands, which can be selectively controlled by electrostatic gating. Our
results put forward twisted bilayer graphene as a simple solid-state platform
to realize triple point fermions at charge neutrality, and demonstrate the
non-trivial role of impurities in moire systems.
