Structural disorder-driven topological phase transition in noncentrosymmetric BiTeI

Abstract

We investigate using local structural disorder to induce a topologically nontrivial phase in a solid state system. Using first-principles calculations, we introduce structural disorder in the trivial insulator BiTeI and observe the emergence of a topological insulating phase. By modifying the bonding environments, the crystal-field splitting is enhanced, with spin-orbit interactions producing a band inversion in the bulk electronic structure. Analysis of the Wannier charge centers and the surface electronic structure reveals a strong topological insulator with Dirac surface states. Finally, we propose a prescription for inducing topological states from disorder in crystalline materials. Understanding how local environments produce topological phases is a key step for predicting disordered and amorphous topological materials.

Structural spillage: an efficient method to identify non-crystalline topological materials

“…When comparing the crystalline Bi 2 Se 3 supercell to the unit cell we obtain a spillage of 2.09 which exactly matches the result given by pymatgen [72]. For the case of disordered BiTeI, previous work showed that small amounts of disorder in the atomic positions cause the system to undergo a topological phase transitions from a trivial insulator (crystal) to a topological insulator (disordered) as a result of an induced band inversion [24]. This is caused by the modified crystal field of the orbitals near the Fermi level which pushes these states closer together when disordered.…”

“…For standard deviations of 0.15Å the deviation from equilibrium position is small which preserves the bulk electronic gap while demonstrating our method works in the presence of disorder. Standard deviations of 0.30Å lead to an average atomic displacement of 0.41Å which is similar to atomic displacements seen in topological materials in the presence of disorder [24]. The structural spillage, shown in Figs.…”

Increased phase coherence length in a porous topological insulator

“…By contrast, on the surface 77 stead of a generic amorphous material [33]. Moreover, an exciting recent study has found that a topological phase transition from trivial insulator to TI can be induced by making a topologically trivial crystalline material either disordered [34] or amorphous [35]. These theoretical studies point to exciting possibilities to discover topological properties in disordered materials, a prospect which has been largely unexplored experimentally.…”

Density-driven higher-order topological phase transitions in amorphous solids

“…Unlike the traditional crystalline solids, the amorphous solids lack long-range order but maintain short-range order due to the random arrangement of internal atoms. Recently, the amorphous topological states, such as topological insulators [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17], topological superconductors [18], and topological metals [19] have been theoretically proposed in amorphous systems. Meanwhile, several experimental works have reported the observations of topological states in amorphous materials, including silica bilayer [20,21] and Bi 2 Se 3 thin film [22].…”