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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.


Real part of the optical conductivity for the bct phase.(a) Black: xx and yy component, (b) red: zz component. The slope parameters Sjj characterizing the constant imaginary parts of the dielectric tensor are also given.
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f11: Real part of the optical conductivity for the bct phase.(a) Black: xx and yy component, (b) red: zz component. The slope parameters Sjj characterizing the constant imaginary parts of the dielectric tensor are also given.

Mentions: The right-hand side of (6) is by a factor 2 smaller than the derivation in ref. 22 but agrees (apart from ħ2 as a misprint) with theoretical studies for systems with electron-hole symmetry and isotropic Dirac cones35. The reciprocal von Klitzing constant leads to the conductivity in SI units. The linear frequency dependence in (6) also appears in Fig. 11 for small frequencies ħω < 0.4 eV independent of the polarization direction. The absolute conductivity values reasonably agree with the measurements2223. The slope coefficient


Electronic and optical properties of topological semimetal Cd 3 As 2
Real part of the optical conductivity for the bct phase.(a) Black: xx and yy component, (b) red: zz component. The slope parameters Sjj characterizing the constant imaginary parts of the dielectric tensor are also given.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
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getmorefigures.php?uid=PMC5382546&req=5

f11: Real part of the optical conductivity for the bct phase.(a) Black: xx and yy component, (b) red: zz component. The slope parameters Sjj characterizing the constant imaginary parts of the dielectric tensor are also given.
Mentions: The right-hand side of (6) is by a factor 2 smaller than the derivation in ref. 22 but agrees (apart from ħ2 as a misprint) with theoretical studies for systems with electron-hole symmetry and isotropic Dirac cones35. The reciprocal von Klitzing constant leads to the conductivity in SI units. The linear frequency dependence in (6) also appears in Fig. 11 for small frequencies ħω < 0.4 eV independent of the polarization direction. The absolute conductivity values reasonably agree with the measurements2223. The slope coefficient

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 &plusmn; near the &Gamma; 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.