Band Structure Engineering of Multinary Chalcogenide Topological Insulators

Abstract

Topological insulators (TIs) have been found in strained binary HgTe and ternary I-III-VI2 chalcopyrite compounds such as CuTlSe2 which have inverted band structures. However, the non-trivial band gaps of these existing binary and ternary TIs are limited to small values, usually around 10 meV or less. In this work, we reveal that a large non-trivial band gap requires the material having a large negative crystal field splitting ${\Delta }_{CF}$ at top of the valence band and a moderately large negative $s-p$ band gap $E_g^{s-p}$. These parameters can be better tuned through chemical ordering in multinary compounds. Based on this understanding, we show that a series of quaternary I2-II-IV-VI4 compounds, including Cu2HgPbSe4, Cu2CdPbSe4, Ag2HgPbSe4 and Ag2CdPbTe4 are TIs, in which Ag2HgPbSe4 has the largest TI band gap of 47 meV because it combines the optimal values of ${\Delta }_{CF}$ and $E_g^{s-p}$.

5 pages, 3 figures

References in corpus (10)

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Cited by in corpus (9)

• False-positive and False-negative assignments of Topological Insulators in Density-Functional Theory and Hybrids
• First-principles calculation of topological invariants Z2 within the FP-LAPW formalism
• Strain tuning of topological band order in cubic semiconductors
• Topological insulators in the quaternary chalcogenide compounds and ternary famatinite compounds
• Three-dimensional topological insulators: A review on host materials
• Finite Size Effects of the Surface States in a Lattice Model of Topological Insulator
• Multiple-$Q$ magnetic orders in Rashba-Dresselhaus metals
• Suppression of lattice thermal conductivity by mass-conserving cation mutation in multi-component semiconductors
• Effects of self-consistent extended Hubbard interactions and spin-orbit couplings on energy bands of semiconductors and topological insulators