Document Type

Article

Publication Date

5-9-2017

Publication Title

Physical Review X

ISSN

2160-3308

Volume

7

Issue

2

DOI

http://dx.doi.org/10.1103/PhysRevX.7.021019

Abstract

We show that the previously predicted “cubic Dirac fermion,” composed of six conventional Weyl fermions including three with left-handed and three with right-handed chirality, is realized in a specific, stable solid state system that has been made years ago, but was not appreciated as a “cubically dispersed Dirac semimetal” (CDSM). We identify the crystal symmetry constraints and find the space group P6_{3}/m as one of the two that can support a CDSM, of which the characteristic band crossing has linear dispersion along the principle axis but cubic dispersion in the plane perpendicular to it. We then conduct a material search using density functional theory, identifying a group of quasi-one-dimensional molybdenum monochalcogenide compounds A^{I}(MoX^{VI})_{3} (A^{I}=Na, K, Rb, In, Tl; X^{VI}=S, Se, Te) as ideal CDSM candidates. Studying the stability of the A(MoX)_{3} family reveals a few candidates such as Rb(MoTe)_{3} and Tl(MoTe)_{3} that are predicted to be resilient to Peierls distortion, thus retaining the metallic character. Furthermore, the combination of one dimensionality and metallic nature in this family provides a platform for unusual optical signature—polarization-dependent metallic vs insulating response.

Creative Commons License

Creative Commons Attribution 4.0 License
This work is licensed under a Creative Commons Attribution 4.0 License.

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