Weak Topological Insulators and Composite Weyl Semimetals: β-Bi4X4 (X=Br, I)

While strong topological insulators (STIs) were experimentally realized soon after they were theoretically predicted, a weak topological insulator (WTI) has yet to be unambiguously confirmed. A major obstacle is the lack of distinct natural cleavage surfaces to test the surface selective hallmark of...

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Bibliographic Details
Published in:Physical review letters 2016-02, Vol.116 (6), p.066801-066801
Main Authors: Liu, Cheng-Cheng, Zhou, Jin-Jian, Yao, Yugui, Zhang, Fan
Format: Article
Language:English
Online Access:Get full text
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Summary:While strong topological insulators (STIs) were experimentally realized soon after they were theoretically predicted, a weak topological insulator (WTI) has yet to be unambiguously confirmed. A major obstacle is the lack of distinct natural cleavage surfaces to test the surface selective hallmark of a WTI. With a new scheme, we discover that β-Bi4X4 (X=Br, I), dynamically stable or synthesized before, can be a prototype WTI with two natural cleavage surfaces, where two anisotropic Dirac cones stabilize and annihilate, respectively. We further find four surface-state Lifshitz transitions under charge doping and two bulk topological phase transitions under uniaxial strain. Near the WTI-STI transition, there emerges a novel Weyl semimetal phase, in which the Fermi arcs generically appear at both cleavage surfaces whereas the Fermi circle only appears at one selected surface.
ISSN:1079-7114
DOI:10.1103/PhysRevLett.116.066801