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AV6Sb6 DFT

\(AV_6Sb_6\) DFT

  • Both \(AV_6Sb_6\) and \(V_6Sb_4\) lack local magnetic interactions and possesses nonmagnetic ground states consistent with experiments.
  • In the presence of the spin-orbit coupling (SOC), the spin rotation symmetry is broken, subsequently, the nodal lines in a system with the coexistence of spatial inversion and Time reversal symmetry are always destroyed.
  • Weak SOC effect.
  • The gap opened at the Dirac band crossings is almost negligible (1MeV for \(CsV_6Sb_6\)).
  • Inclusion of Hubbard U in the DFT calculations does not change the band topology, and the Dirac nodal lines remain intact with U = 2.0 eV.

\(CsV_6Sb_6\) Band structure

CsV6Sb6_bands.png - The DOS in the vicinity of Fermi level are dominated by V-3d orbitals for \(CsV_6Sb_6\) and \(V_6Sb_4\), whereas the Sb-p orbitals have weak contributions. - Shows linear band crossings that are close to Fermi level along the high symmetry points. - The electronic structure of the bilayer compound is distinct from that of single layer AV3Sb5 family which are hallmarked by multiple Dirac crossings(AV3Sb5 DFT) and saddle points near Fermi level - Due to the three-fold rotational symmetry, there are three equivalent middle planes, and thus six type-II Dirac nodal lines that are symmetrically distributed in the BZ of \(CsV_6Sb_6\). - Very weak SOC effect and hence Dirac nodal lines are intact.

\(V_6Sb_4\) Band structure

V6Sb4_bands.png - The crossings of valence and conduction bands are absent along Γ/Z-L in the band structure of V6Sb4 (Fig. 2b). However, the preserved band crossings along Γ/Z-F can still form symmetry-protected nodal lines on three equivalent middle planes.