Fig. 4: Topological character of band structures in the normal 1T phase for Ti-doped VTe2.
From: Switching of band inversion and topological surface states by charge density wave
a The Brillouin zone of 1T phase. kx, ky, and kz indicate the axes in the reciprocal space corresponding with the global xyz axes (see Fig. 1a) used for the calculation in b. b The bulk band calculations of 1T-V0.87Ti0.13Te2 along kΓM direction at several kz values (0, 0.38, 0.76, 1.00 π/c). The color of the curves indicates the weight of orbital characters, as shown by the color-scale. The “+” and “−” mark the even and odd parity, respectively. The broken curves represent the results without spin-orbit coupling. c, d The corresponding (0 0 1) slab calculations along the \({\bar{\mathrm{\Gamma }}} - {\bar{\mathrm{M}}}\) (c) and the \({\bar{\mathrm{K}}} - {\bar{\mathrm{M}}} - {\bar{\mathrm{K}}}\) (d) lines, respectively. e ARPES image of 1T-V0.90Ti0.10Te2 along the \({\bar{\mathrm{K}}} - {\bar{\mathrm{M}}} - {\bar{\mathrm{K}}}\) direction recorded using a He-discharge lamp (21.2 eV, 350 K). The red (blue) marks represent the peak positions of energy (momentum) distribution curves. f Fermi surface image of 1T-V0.87Ti0.13Te2 in the kz = 0 plane (circular polarized 83 eV photons, 300 K), with an energy window of ±5 meV. The red curves display the Fermi surface schematically. g Schematic 2D BZ. The red arrow indicates the measurement region of hν-dependent ARPES. h–j hν-dependent ARPES spectra of 1T-V0.90Ti0.10Te2 with 63 eV (h), 69 eV (i), and 78 eV (j) photons (circular polarization, 320 K), which respectively detects at kz = 0, π/2c, and π/c plane. The circles with vertical (horizontal) error bars represent the EDC’s (MDC’s) peak positions. k Schematic band dispersion along \({\bar{\mathrm{K}}} - {\bar{\mathrm{M}}} - {\bar{\mathrm{K}}}\) with experimentally obtained peak plots. The red, green, and blue markers are the peak plots for hν = 63, 69, and 78 eV, respectively from h–j. The orange curve represents the schematic of the Dirac surface state (DSS), whereas the blurred gray curves are the bulk bands (Bulk A and B).
