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arXiv · 2401.13930

Ideal Spin-Orbit-Free Dirac Semimetal and Diverse Topological Transitions in Pr$_8$CoGa$_3$ Family

Manabu Sato·Juba Bouaziz·Shuntaro Sumita·Shingo Kobayashi·Ikuma Tateishi·Stefan Blügel·Akira Furusaki·Motoaki Hirayama
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Abstract

Topological semimetals, known for their intriguing properties arising from band degeneracies, have garnered significant attention. However, the discovery of a material realization and the detailed characterization of spinless Dirac semimetals have not yet been accomplished. Here, we propose from first-principles calculations that the $RE_8\mathrm{Co}X_3$ group ($RE$ = rare earth elements, $X$ = Al, Ga, or In) contains ideal spinless Dirac semimetals whose Fermi surfaces are fourfold degenerate band-crossing points (without including spin degeneracy). Despite the lack of space inversion symmetry in these materials, Dirac points are formed on the rotation-symmetry axis due to accidental degeneracies of two bands corresponding to different 2-dimensional irreducible representations of $C_{6v}$ group. We also investigate, through first-principles calculations and effective model analysis, various phase transitions caused by lattice distortion or elemental substitutions from the Dirac semimetal phase to distinct topological semimetallic phases such as nonmagnetic linked-nodal-line and Weyl semimetals (characterized by the second Stiefel-Whitney class) and ferromagnetic Weyl semimetals.

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Manabu Sato, Juba Bouaziz, Shuntaro Sumita, Shingo Kobayashi, Ikuma Tateishi, Stefan Blügel, Akira Furusaki, Motoaki Hirayama. 2024-01-25. Ideal Spin-Orbit-Free Dirac Semimetal and Diverse Topological Transitions in Pr$_8$CoGa$_3$ Family. https://doi.org/10.1038/s43246-024-00635-9

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