Figure 1

(a) and (b) FS mapping measured with 65 eV photons at 10 K using $p$ and $s$ polarization, respectively. The maps are obtained by integrating raw spectra over the energy window ($E_F\pm 10\mathrm{meV}$) and by symmetrizing the $\pi /4$ FS. (c) and (e) The large energy scale ARPES images together with the LDA calculations at different values of $k_z$ (solid lines) along the $\Gamma M$ line using $p$ and $s$ polarization, respectively, where the LDA calculations are expanded by a factor of 1.1 to roughly align the O $2p$ position. (d) and (f) Same as panels (c) and (e) except that measured line is the $\Gamma X$ line. Considering the ARPES matrix element effects, we have chosen the excitation energy and the location of the Brillouin zone (BZ) to obtain clear band dispersions: (c) 88-eV in the 2nd BZ, (e) 88-eV in the 1st BZ, (d) 54-eV in the 2nd BZ, and (f) 38-eV in the 1st BZ. (g) and (h) Schematic electronic structure along $\Gamma M$ and $\Gamma X$ line, respectively. The solid lines represent the LDA calculation results renormalized by EEI from the LDA calculations (dashed lines). Note that the orbital assignment along the $\Gamma X$ line can be varied depending on the $k_z$ value [13].Reuse & Permissions

Figure 2

(a) and (b) The momentum distribution curves (MDCs) at $E_F$ for $p$ polarization (upper) and $s$ polarization (lower) sliced from the FS along $\Gamma M$ and $\Gamma X$ lines, respectively [white lines in Figs. 1a, 1b ]. (c) and (d) ARPES images in the $k_{\parallel }-k_z$ plane acquired with 22 to 70 eV photons at 10 K using $p$ polarization along the $\Gamma M$ and $\Gamma X$ planes, respectively. The ARPES images were obtained by integrating raw spectra over the energy window ($E_F\pm 10\mathrm{meV}$). The experimentally determined $k_z$ dispersion is indicated by grey, red, and blue marks for $\alpha$, $\beta$, and $\gamma$ FS sheets, respectively. (e) and (g) Theoretical $k_z$ dispersions along the $\Gamma M$ ($ZM$) plane calculated by LDA and LDA with the SOI, respectively. (f) and (h) Same as (e) and (g), except that the plane is perpendicular to the $\Gamma X$ ($ZX$) line.Reuse & Permissions

Figure 3

(a) and (b) ARPES images acquired along the $\Gamma M$ line (yellow line in inset) with 48-eV photons using $p$- and $s$-polarization, respectively. (c) MDC-derived energy-momentum dispersions of the $\beta$ (red marks) and the $\gamma$ (blue marks) sheets, where the $\beta$ sheet includes an offset of $-0.1{\AA }^{-1}$. The solid and dashed lines represent the model dispersions [top panel of (d)] and the Fermi velocities in each sheet, respectively. In panels (a)–(c), the MDC dispersions are replaced by the linear function below 15 meV because of an energy-resolution effect [27], but this operation does not affect our conclusions. (d) Top panel shows the calculated phenomenological model dispersions [21]. Middle and bottom panels show the orbital components of the $\gamma$ and $\beta$ sheets, respectively. The experimentally determined $k_F$ for the $\beta$ and $\gamma$ sheets is indicated by the dashed lines in (d). (e) The MDC dispersions of the $\gamma$ sheet are closing up in the different regions, which are indicated by arrows in (c), where LEK, MEK, and HEK of the $\gamma$-sheet dispersion are highlighted in the top, middle, and bottom panels, respectively. (f) ARPES image measured at 100 K, $s$ polarization, with 32-eV photons along the $\Gamma M$ line divided by the Fermi-Dirac distribution. (g) Comparison between ARPES and calculated band dispersions.Reuse & Permissions