Weak Topological Insulators and Composite Weyl Semimetals: β-Bi₄Χ₄ (Χ = Br, I)

Date

2016-02-09

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Publisher

Amer Physical Soc

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Abstract

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-Bi₄Χ₄ (Χ = 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.

Description

Includes supplementary material.

Keywords

Phase transformations (Statistical physics)l, Weak interactions (Nuclear physics), Strong interactions (Nuclear physics, Bi4br4

item.page.sponsorship

Aspen Center for Physics (NSF grant no. 1066293); Kavli Institute for Theoretical Ohysics (NSF grant no. PHY11-25915); the MOST Project of China (no. 2014CB920903 and no. 2013CB921903); NSFC (grants no. 11574029, no.11404022, and no 11225418); the Specialized Research Fund for the Doctoral Program of Higher Education of China (grant no. 20121101110046); the BIT Basic Research Funds (grant no. 20141842001).

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©2016 American Physical Society. All rights reserved

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