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Electronic and optical properties of topological semimetal Cd 3 As 2

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ABSTRACT

K: Using ab initio density functional theory the band structure and the dielectric function of a bct Cd3As2 crystal are calculated. We find a Dirac semimetal with two Dirac nodes ± near the Γ point on the tetragonal axis. The bands near the Fermi level exhibit a linear behavior. The resulting Dirac cones are anisotropic and the electron-hole symmetry is destroyed along the tetragonal axis. Along this axis the symmetry-protected band linearity only exists in a small energy interval. The Dirac cones seemingly found by ARPES in a wider energy range are interpreted in terms of pseudo-linear bands. The behavior as 3D graphene-like material is traced back to As p orbital pointing to Cd vacancies, in directions which vary throughout the unit cell. Because of the Dirac nodes the dielectric functions (imaginary part) show a plateau for vanishing frequencies whose finite value is proportional to the Sommerfeld fine structure constant but varies with the light polarization. The consequences of the anisotropy of the Dirac cones are highlighted for the polarization dependence of the infrared optical conductivity.

No MeSH data available.


Electronic band structure of the bct Cd3As2 superstructure with SOI.(a) bct BZ with indication of high-symmetry lines and dots. (b) Bands versus high-symmetry lines. The Fermi energy is used as energy zero.
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f5: Electronic band structure of the bct Cd3As2 superstructure with SOI.(a) bct BZ with indication of high-symmetry lines and dots. (b) Bands versus high-symmetry lines. The Fermi energy is used as energy zero.

Mentions: The Cd3As2 band structure calculated with SOI for the relaxed geometry is plotted in Fig. 5 versus high-symmetry lines in the bct BZ. No spin splitting of the bands is visible because of the presence of inversion symmetry. The absolute positions of the band energies, the band dispersions, and the band splittings on the BZ boundary along XP and PN are very similar to those calculated by means of the experimentally determined centrosymmetric geometry and an all-electron DFT approach21. All bands are at least twofold degenerate. However, also the non-centrosymmetric bct crystal and a different DFT approach based on projector-augmented waves give very similar results13, because of the rather small spin splittings.


Electronic and optical properties of topological semimetal Cd 3 As 2
Electronic band structure of the bct Cd3As2 superstructure with SOI.(a) bct BZ with indication of high-symmetry lines and dots. (b) Bands versus high-symmetry lines. The Fermi energy is used as energy zero.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5382546&req=5

f5: Electronic band structure of the bct Cd3As2 superstructure with SOI.(a) bct BZ with indication of high-symmetry lines and dots. (b) Bands versus high-symmetry lines. The Fermi energy is used as energy zero.
Mentions: The Cd3As2 band structure calculated with SOI for the relaxed geometry is plotted in Fig. 5 versus high-symmetry lines in the bct BZ. No spin splitting of the bands is visible because of the presence of inversion symmetry. The absolute positions of the band energies, the band dispersions, and the band splittings on the BZ boundary along XP and PN are very similar to those calculated by means of the experimentally determined centrosymmetric geometry and an all-electron DFT approach21. All bands are at least twofold degenerate. However, also the non-centrosymmetric bct crystal and a different DFT approach based on projector-augmented waves give very similar results13, because of the rather small spin splittings.

View Article: PubMed Central - PubMed

ABSTRACT

K: Using ab initio density functional theory the band structure and the dielectric function of a bct Cd3As2 crystal are calculated. We find a Dirac semimetal with two Dirac nodes ± near the Γ point on the tetragonal axis. The bands near the Fermi level exhibit a linear behavior. The resulting Dirac cones are anisotropic and the electron-hole symmetry is destroyed along the tetragonal axis. Along this axis the symmetry-protected band linearity only exists in a small energy interval. The Dirac cones seemingly found by ARPES in a wider energy range are interpreted in terms of pseudo-linear bands. The behavior as 3D graphene-like material is traced back to As p orbital pointing to Cd vacancies, in directions which vary throughout the unit cell. Because of the Dirac nodes the dielectric functions (imaginary part) show a plateau for vanishing frequencies whose finite value is proportional to the Sommerfeld fine structure constant but varies with the light polarization. The consequences of the anisotropy of the Dirac cones are highlighted for the polarization dependence of the infrared optical conductivity.

No MeSH data available.