Inversion-symmetry protected chiral hinge states in stacks of doped quantum Hall layers

We prove the existence of higher-order topological insulators with protected chiral hinge modes in quasi-two-dimensional systems made out of coupled layers stacked in an inversion-symmetric manner. In particular, we show that a homogeneous external magnetic field slightly tilted away from the stacking direction drives alternating p- and n-doped honeycomb sheets into a higher-order topological phase, characterized by a nontrivial three-dimensional Z2 invariant. We identify graphene, silicene, and phosphorene multilayers as potential material platforms for the experimental detection of this second-order topological insulating phase.