Robustness of gapless interface states in a junction of two topological insulators

Abstract

We theoretically study subgap states appearing at the interface between two three-dimensional topological insulators which have different configurations in the spin-orbit interactions from each other. The coupling of spin σ with momenta p is configured by a material dependent 3 × 3 matrix as σ μ ν μ p ν . The spectra of the interface subgap states depend on the relative choices of 's in the two topological insulators where the two are connected by the unitary transformation including the inversion and the rotation in momentum space. The gapless states appear at the interface when the transformation includes the inversion. The two topological insulators can be distinguished by using the topological numbers defined in the two-or one-dimensional partial Brillouin zone, which explains the presence of the gapless interface states. We also discuss the robustness of such gapless states under perturbations breaking the time-reversal symmetry or the band-inversion symmetry.

Topological Surface State Annihilation and Creation in SnTe/Crx(BiSb)2–xTe3 Heterostructures

“…Such annihilation fundamentally changes the number of surface states, altering the electronic properties of the heterostructure system. While surface state interaction at TI interfaces is a subject of enormous interest in theory, ,− experimental studies have been very limited to date.…”

Crystalline topological states at a topological insulator junction

“…For the Bi 2 Se 3 class of TIs, n M = ±1, where the sign determines the spin chirality of the surface states (handedness of the spin texture) and the absolute value gives the number of surface Dirac cones [15][16][17][18] . Hence, gapless modes should also exist at any mirror-symmetric interface between TIs with opposite spin chirality since this corresponds to a change ∆n M = 2 [19][20][21][22] .…”

Transport in a thin topological insulator with potential and magnetic barriers

“…Various properties of junctions between different surfaces of TIs have been studied in Refs. [18][19][20][21][22][23][24]. Junctions of surfaces of a TI with normal metals, magnetic materials and superconductors have also been studied [25][26][27] .…”