Bi₂Se₃/Bi₂Se₃ and TlSe/TlSe junctions: enhanced coupling of topological interface states by intercalation

Abstract

Based on first-principles calculations, we studied the coupling of topological interface states at the interface of Bi2Se3/Bi2Se3 and TlSe/TlSe junctions. From our calculations, the coupling leads to an energy gap at the Dirac point of topological interface states and the energy gap is an exponential decay function of interface spacing when the interface spacing is large enough. The law of exponential decay may be used to identify the formation of interface states from interface-bulk mixed states. It also suggests that the coupling is caused by quantum tunneling. The coupling of the interface states in TlSe/TlSe can be greatly enhanced by intercalating hexagonal BN, although hexagonal BN is often used as a 2D substrate or insulator. The intercalation of bilayer BN or single atomic Au layer can further enhance the interfacial coupling. Our calculations may be helpful for the application of junctions composed of topological insulators.

Tuning the Bandgap of Topological Edge States by Inclined‐Electric Field

“…The coupling of topological surface states was studied in details. [ 17 ] The coupling can be greatly enhanced by intercalating h‐BN at interface. Moreover, the coupling leads to an energy gap at the Dirac point of topological surface states, and the energy gap is an exponential decay function of interface spacing when the interface spacing is large enough.…”

“…Due to the finite size effect, the coupling of topological edge or surface states opens a nonzero bandgap in the edge or surface states. [ 13–17 ] Besides, the topological edge or surface states from two TIs can also be coupled with each other and have a nonzero bandgap in the junctions composed of TIs. [ 18–22 ]…”

“…Due to the finite size effect, the coupling of topological edge or surface states opens a nonzero bandgap in the edge or surface states. [13][14][15][16][17] Besides, the topological edge or surface states from two TIs can also be coupled with each other and have a nonzero bandgap in the junctions composed of TIs. [18][19][20][21][22] The introduction of electric field may be a favorable and promising method to regulate the topological edge states.…”

Enhanced Magnetic Anisotropy and Curie Temperature by the Absence of Se Atoms at the Interface of EuS/Bi2Se3

“…[37,38] The DFT-D3 method was used to consider the van der Waals correction. [16,39] To better describe the strong correlation effect of the Eu-f orbital, on-site Hubbard interaction was considered as a common value of U = 8 eV and J = 1 eV, respectively. [40] We used 1 Â 1 supercell to build the Se interface and Bi interface models as shown in Figure 1.…”

“…Bi 2 Se 3 is a well-known topological insulator with strong spin-orbit coupling (SOC) and a large bandgap of 0.33 eV. [14][15][16][17] On the other hand, EuS is a well-behaved Heisenberg ferromagnetic insulator. Moreover, ultrathin EuS layers are stable with good growth characteristics and clean interfaces on a variety of materials.…”