Potential ring of Dirac nodes in a new polymorph of Ca$_3$P$_2$

Lilia S. Xie; Leslie M. Schoop; Elizabeth M. Seibel; Quinn D. Gibson; Weiwei Xie; Robert J. Cava

doi:10.1063/1.4926545

paper

Potential ring of Dirac nodes in a new polymorph of Ca $_{3}$ P $_{2}$

arXiv:1504.01731 · doi:10.1063/1.4926545

Abstract

We report the crystal structure of a new polymorph of Ca $_{3}$ P $_{2}$ , and an analysis of its electronic structure. The crystal structure was determined through Rietveld refinements of powder synchrotron x-ray diffraction data. Ca $_{3}$ P $_{2}$ is found to be a variant of the Mn $_{5}$ Si $_{3}$ structure type, with a Ca ion deficiency compared to the ideal 5:3 stoichiometry to yield a charge-balanced compound. We also report the observation of a secondary phase, Ca $_{5}$ P $_{3}$ H, in which the Ca and P sites are fully occupied and the presence of interstitial hydride ions creates a closed-shell electron-precise compound. We show via electronic structure calculations of Ca $_{3}$ P $_{2}$ that the compound is stabilized by a gap in the density of states compared to the hypothetical compound Ca $_{5}$ P $_{3}$ . Moreover, the calculated band structure of Ca $_{3}$ P $_{2}$ indicates that it should be a three-dimensional Dirac semimetal with a highly unusual ring of Dirac nodes at the Fermi level. The Dirac states are protected against gap opening by a mirror plane in a manner analogous to graphene. The results suggest that further study of the electronic properties of Ca $_{3}$ P $_{2}$ will be of interest.

Potential ring of Dirac nodes in a new polymorph of Ca $_{3}$ P $_{2}$

Abstract

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Potential ring of Dirac nodes in a new polymorph of Ca3​P2​

Abstract

References in corpus (17)

Cited by in corpus (200)

Potential ring of Dirac nodes in a new polymorph of Ca $_{3}$ P $_{2}$