Intrinsic topological metal state in T-graphene

Abstract

An intrinsic topological metal 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 topological metal 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.

Novel 2D carbon material T-graphene supported 3d transition metal single atoms as efficient oxygen reduction catalysts

“…T-graphene 43 was predicted to have low cohesive energy, high in-plane stiffness and bulk modulus, suggesting its high stability. Moreover, Yan et al 44 theoretically predicted that T-graphene is an intrinsic topological metal and Gu et al 45 predicted that T-graphene is an intrinsic two-dimensional (2D) superconductor, suggesting that T-graphene has excellent conductivity. Therefore, it is highly significant to systematically calculate the ORR activity of T-graphene supported TMN 4 /TMC 4 SACs (marked as TM-Tgra) and clarify the differences in geometric and electronic structures between TM-Tgra and its graphene supported counterparts (marked as TM-Gra).…”

Higher-order topological states in T-graphene and their realization in photonic crystals

“…The non-trivial topological properties can be characterized by the polarization because of its symmetries. Previous work reported it holds exotic topological phase transition: from topological metal to topological insulator when adjusting the hoppings [21]. We will show that it also holds abundant higherorder topological phases.…”

“…For cases of P x = 1 2 , P y = 0 or P y = 1 2 , P x = 0, there are only edge states along y direction or x direction without corner states. Although the edge states have been studied [21], the corner states have not been concerned.…”

“…Further increasing |v/u| > 2, the local edge state becomes global, as given in figure 2(d), which means it reaches the topological insulator phase. The edge states have been studied in [21].…”

“…The exploration for topological physics [1][2][3][4][5][6][7][8] has brought out diverse topological materials, including topological insulators [9][10][11][12][13][14][15], topological semimetals [16][17][18], topological metal [19][20][21], and topological superconductors [22]. They can also be classified by multiple symmetries [23].…”