Intrinsic topological metal state in T-graphene

Abstract An intrinsic topological metal (TM) state is found in the T-graphene, a monolayer with both the time-reversal symmetry and the four-fold symmetry. The state distinguishes itself by the nontrivial electric polarization from the ordinary metals and features with two local edge states in the corresponding nanoribbons. The TM state is confirmed as a transition state bridging the ordinary metal state and the topological insulator state when the relative neighboring hoppings change in the lattice. The topological nature is further verified by checking the robustness of transport property against randomly-introduced strong disorders. The fact that the multiple topological states indexed by different parameters coexist in such a practical system shows a broad prospect in versatile topological transport devices.