Fig. 2: Fermi surface, susceptibility functions, phonon dispersion and charge density wave of SrAl4.
From: Origin of charge density wave in topological semimetals SrAl4 and EuAl4
a SrAl4 Fermi surface (FS) consists of valence (yellow outside and blue inside) and conduction band (purple outside and green inside) from the side-view. The individual FS pieces of valence and conduction bands from the near top-view are in b, c, respectively. d 3D real part of the susceptibility function (χ(q)) as in Reχ(q)/Reχmax of SrAl4 with the iso-surface value of 0.999 showing the maximum at q=±0.23(π/c). e The imaginary part of the susceptibility functions Imχ(q)/Imχmax along the Γ-Z direction for the four compounds. The vertical dashed line marks the experimental charge density wave (CDW) vector for SrAl4 at qCDW = 0.22(π/c). f 2D FS cut on the (110) plane showing the FS shells of the valence and conduction bands in SrAl4 with the nesting vector marked by an orange arrow. The high (low) intensity is in red (grey). g The real part of the susceptibility functions Reχ(q)/Reχmax along the Γ-Z direction. h Phonon band dispersion ω(q) of SrAl4 with imaginary transverse acoustic (TA) mode along the Γ-Z direction (black arrow).
