Exploring strong and weak topological states on isostructural substitutions in TlBiSe2

Topological Insulators (TIs) are unique materials where insulating bulk hosts linearly dispersing surface states protected by the Time-Reversal Symmetry. These states lead to dissipationless current flow, which makes this class of materials highly promising for spintronic applications. Here, we predict TIs by employing state-of-the-art first-principles based methodologies, viz., density functional theory and many-body perturbation theory (G0W0) combined with spin-orbit coupling effects. 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. 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, besides, we report six weak Topological Insulators, 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.