TlBiSe2中同构取代的强、弱拓扑态探索
Exploring strong and weak topological states on isostructural substitutions in TlBiSe2
摘要：
拓扑绝缘体（TI）是一类独特的材料，其绝缘体具有线性分散的表面态，这些表面态受时间约束对称性（TRS）的保护。这些状态导致无耗散电流，这使得这类材料在自旋电子学应用中非常有前途。在这里，我们通过高通量筛选预测新的TI，采用最先进的第一原理为基础的方法，即，密度泛函理论（DFT）和多体微扰理论（G0W 0）结合自旋轨道耦合（SOC）。为此，我们采取了一个众所周知的三维TI，TlBiSe 2，并在不同的网站进行完全取代与合适的材料，以检查所获得的同构材料是否表现出拓扑特性。随后，我们扫描这些材料的基础上SOC诱导的宇称反转在时间相关不变矩（TRIM）。随后，为了确认所选材料的拓扑性质，我们绘制了它们的表面状态以及Z2不变量的计算。结果表明，GaBiSe 2是一种强拓扑绝缘体（STI）.此外，我们还报道了六种弱拓扑绝缘体，即PbBiSe_2，SnBiSe_2，SbBiSe_2，Bi_2Se_2，TlSnSe_2和PbSbSe_2。我们进一步验证了所有报道的TI都是动态稳定的，显示了所有真实的声子振动模式。
英文摘要：
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.
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