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arXiv · 1511.03221

Non-stoichiometry and Defects in the Weyl Semimetals TaAs, TaP, NbP, and NbAs

Tiglet Besara·Daniel Rhodes·Kuan-Wen Chen·Qui Zhang·Bin Zeng·Yan Xin·Luis Balicas·Ryan E. Baumbach·Theo Siegrist
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Abstract

We report a structural study of the Weyl semimetals TaAs, TaP, NbP, and NbAs, utilizing diffraction techniques (single crystal x-ray diffraction and energy dispersive spectroscopy) and imaging techniques (transmission electron microscopy/scanning transmission electron microscopy). We observe defects of various degrees, leading to non-stoichiometric single crystals of all four semimetals. While TaP displays a large pnictide deficiency with composition TaP$_{0.83(3)}$, and stacking faults accompanied by anti-site disorder and site vacancies, TaAs displays transition metal deficiency with composition Ta$_{0.92(2)}$As and a high density of stacking faults. NbP also displays pnictide deficiency, yielding composition NbP$_{0.95(2)}$, and lastly, NbAs display very little deviation from a 1:1 composition, NbAs$_{1.00(3)}$, and is therefore recommended to serve as the model compound for these semimetals.

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Tiglet Besara, Daniel Rhodes, Kuan-Wen Chen, Qui Zhang, Bin Zeng, Yan Xin, Luis Balicas, Ryan E. Baumbach, Theo Siegrist. 2015-11-19. Non-stoichiometry and Defects in the Weyl Semimetals TaAs, TaP, NbP, and NbAs. https://doi.org/10.1103/physrevb.93.245152

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