New Class of 3D Topological Insulator in Double Perovskite

Abstract

We predict a new class of 3D topological insulators (TIs) in which the spin-orbit coupling (SOC) can more effectively generate band gap. Band gap of conventional TI is mainly limited by two factors, the strength of SOC and, from electronic structure perspective, the band gap when SOC is absent. While the former is an atomic property, the latter can be minimized in a generic rock-salt lattice model in which a stable crossing of bands at the Fermi level along with band character inversion occurs in the absence of SOC. Thus large-gap TIs or TIs composed of lighter elements can be expected. In fact, we find by performing first-principles calculations that the model applies to a class of double perovskites ABiXO (A = Ca, Sr, Ba; X = Br, I) and the band gap is predicted up to 0.55 eV. Besides, surface Dirac cones are robust against the presence of dangling bond at boundary.

First‐Principles Prediction of a New Family of Layered Topological Insulators

“…Since then, TIs have attracted tremendous attention due to their fundamental interest as well as potential applications . A great many 3D TIs have been proposed, but only a few of them have been experimentally synthesized and veryfied, among which only the TIs of the Bi 2 Se 3 family have been widely and intensively studied. This family of TIs have large energy gaps (typically, 0.3 eV for Bi 2 Se 3 ), enough for room temperature utilizations; they are van der Waals (vdW)‐layered, so defective surface states can be largely avoided and the lattice matching requirement can be significantly reduced in epitaxial growth on substrates.…”

Superconducting Long-Range Proximity Effect through the Atomically Flat Interface of a Bi2Te3 Topological Insulator

“…[25][26][27][28] In this respect, the interface between superconductors (S) and a topological insulator (TI) is expected to induce by proximity peculiar properties such as unconventional superconductivity. 20,25 Topologically protected surface states [29][30][31][32][33][34][35][36][37] are not only attractive from the fundamental point of view, such as the realization of Majorana modes, [38][39][40] but also for spintronics applications, in the view of their robustness and the forbidden backscattering. [41][42][43] The couple Pb/Bi 2 Te 3 is a good candidate for such a study.…”

Disorder-Promoted Splitting in Quasiparticle Interference at Nesting Vectors

“…The amplitude of the splitting allows evaluating the lifetime of the electrons. A similar phenomenon should be observed in any system with a well-defined scattering vector regardless of its topological properties.Predicted a long ago, recently discovered three-dimensional topological insulators (TIs) [1][2][3][4][5][6][7] are characterized by conducting surface states with the linear dispersion, Dirac cones, evolving in the bulk gap. In real materials, the Dirac cones are often regular only close to their origin, the Dirac point (DP).…”