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Nonstoichiometry and Weyl fermionic behavior in TaAs

Buckeridge, J; Jevdokimovs, D; Catlow, CRA; Sokol, AA; (2016) Nonstoichiometry and Weyl fermionic behavior in TaAs. Physical Review B , 94 (18) , Article 180101(R). 10.1103/PhysRevB.94.180101. Green open access

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Abstract

The band structure of TaAs provides the necessary conditions for the emergence of Weyl fermions. Measurements verifying this fact are remarkably robust, given the reported levels of nonstoichiometry in typical single crystals. Here we demonstrate the surprising fact that a small degree of nonstoichiometry is essential for such observations in a wide range of temperatures. From first principles, we compute how crystal defects influence the position of the Fermi level relative to the so-called Weyl points, a key factor in allowing the detection of these particles. We show that observations of Weyl fermions depend crucially on nonstoichiometry and only occur within narrow ranges of elemental composition and temperature, indicating a considerable degree of fortuity in their discovery. Our approach suggests that in some cases the drive to produce ultra-pure crystals for measurements of exotic emergent phenomena may be misplaced.

Type: Article
Title: Nonstoichiometry and Weyl fermionic behavior in TaAs
Open access status: An open access version is available from UCL Discovery
DOI: 10.1103/PhysRevB.94.180101
Publisher version: https://doi.org/10.1103/PhysRevB.94.180101
Language: English
Additional information: Published by the American Physical Society under the terms of the Creative Commons Attribution 3.0 License (https://creativecommons.org/licenses/by/3.0/). Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.
UCL classification: UCL
UCL > Provost and Vice Provost Offices > UCL BEAMS
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Chemistry
URI: https://discovery.ucl.ac.uk/id/eprint/1527389
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