Topological insulators double perovskites: A2TePoO6 (A = Ca, Sr, Ba)

Abstract

Based on first-principle calculations and direct density functional theory calculations of surface bands, we predict a new class of three-dimensional (3D) Z2 topological insulators (TIs) with larger bulk bandgaps up to 0.4 eV in double perovskite materials A2TePoO6 (A = Ca, Sr, and Ba). The larger nontrivial gaps are induced by the symmetry-protected band contact along with band inversion occurring in the absence of spin-orbit coupling (SOC) making the SOC more effective than conventional TIs. The proposed materials are chemically inert and more robust to surface perturbations due to its intrinsic protection layer. This study provides the double perovskite material as a rich platform to design new TI-based electronic devices.

Large Bandgap Topological Insulator in Oxide APoO3 (A = Be, Mg, Ca, Sr, Ba, and Ra) Perovskite: An Ab Initio Study

“…Several kinds of crystal structures are found or predicted to have a topological insulator phase: for example, Bi 2 Te 3 [1] and Bi 2 Se 3 [1] in the hexagonal structure; LaPtBi [10,11] half-Heusler compound [9,[12][13][14][15][16][17], oxide perovskite [18,19], halide perovskite [20][21][22], binary compound [23], Ba 2 BiIO 6 [24], and CaTePoO 6 [25] double perovskites in the cubic structure. The bulk bandgap for these Tls are in general smaller than 0.5 eV; for example, bismuth-based compounds such as Bi 2 Te 3 [26] are 0.17 eV, Bi 2 Te 2 S [27] 0.3 eV, and PbBi 4 Te 4 S 3 is 0.2 eV in the experiment and 0.3 eV in theory.…”

“…For example, the bandgaps for Ba 2 BiIO 6 [24], Sr 2 BiIO 6 [24], Ca 2 BiIO 6 [24], Ba 2 BiBrO 6 [24], Sr 2 BiBrO 6 [24], and Ca 2 BiBrO 6 [24] are 0.55, 0.53, 0.52, 0.33, 0.32, and 0.34 eV, respectively. Ca 2 TePoO 6 [25], Sr 2 TePoO 6 [25], and Ba 2 TePoO 6 [25] double perovskites are also predicted to have theoretically large bandgap topological insulators, with bandgaps of 0.325, 0.400, and 0.375 eV, respectively.…”

Topological and thermoelectric properties of double antiperovskite pnictides

“…12 Doubling the structures will affect the dispersion and have been suggested in certain cases to increase the topological insulator's bulk energy gap. 13,14 In this paper, we study the topological nature and the electronic structure based thermoelectric properties of several pnictide-based double antiperovskites, based on our previous study on single antiperovskite compounds 15 . Our methods of calculations are described in Sec.…”

“…Their electronic structures often display a narrow gap with band minimum and maximum at high symmetry points [9][10][11], implying that these materials may have potential in thermoelectric applications [12]. Doubling the structures will affect the dispersion and have been suggested in certain cases to increase the topological insulator's bulk energy gap [13,14].…”