Exploring strong and weak topological states on isostructural substitutions in TlBiSe2

TL;DR

This study uses advanced computational methods to identify new topological insulators by substituting elements in TlBiSe2, revealing one strong and six weak topological insulators with potential spintronic applications.

Contribution

The paper introduces a high-throughput first-principles screening approach to discover new topological insulators through isostructural substitutions in TlBiSe2.

Findings

GaBiSe2 is a Strong Topological Insulator.

Six materials identified as Weak Topological Insulators.

All reported TIs are dynamically stable with real phonon modes.

Abstract

Topological Insulators (TIs) are unique materials where insulating bulk hosts linearly dispersing surface states protected by the Time-Reversal Symmetry (TRS). These states lead to dissipationless current flow, which makes this class of materials highly promising for spintronic applications. Here, we predict new TIs via high-throughput screening by employing state-of-the-art first-principles based methodologies, viz., Density Functional Theory (DFT) and many-body perturbation theory (G0W0) combined with Spin-Orbit Coupling (SOC). For this, we take a well-known 3D TI, TlBiSe2 and perform complete substitution with suitable materials at different sites to check if the obtained isostructural materials exhibit topological properties. Subsequently, we scan these materials based on SOC-induced parity inversion at Time-Reversal Invariant Momenta (TRIM). Later, to confirm the topological nature of selected materials, we plot their surface states along with calculation of Z2 invariants. Our results show that GaBiSe2 is a Strong Topological Insulator (STI). Besides, we report six Weak Topological Insulators (WTIs) viz. PbBiSe2, SnBiSe2, SbBiSe2, Bi2Se2, TlSnSe2 and PbSbSe2. We have further verified that all the reported TIs are dynamically stable showing all real phonon modes of vibration.