Dependence of Band-Renormalization Effects on the Number of Copper Oxide Layers in Tl-Based Copper Oxide Superconductors Revealed by Angle-Resolved Photoemission Spectroscopy

Here we report the first angle-resolved photoemission measurement on nearly optimally doped multilayer Tl-based superconducting cuprates (Tl-2212 and Tl-1223) and a comparison study to single-layer (Tl-2201) compound. A “kink” in the band dispersion is found in all three compounds but exhibits different momentum dependence for the single-layer and multilayer compounds, reminiscent to that of Bi-based cuprates. This layer number dependent renormalization effect strongly implies that the spin-resonance mode is unlikely to be responsible for the dramatic renormalization effect near the antinodal region.

Figure 1

(a) The Fermi surface obtained by integrating spectra (taken at 20 K) within an energy window of $E_F\pm 10\mathrm{meV}$ (upper panels) and their EDCs near $k_F$ along the Fermi surface (lower panels). The momentum positions of these EDCs were indicated by the square markers. All data were taken in the second Brillouin zone and plotted in the first zone under the reduced zone scheme. The Fermi surface map of Tl-2212 is symmetrized with respect to the diagonal of the zone. (b) Integrated EDCs at the antinodal region of Tl-2212 (inset) in a cycle of temperature dependence measurements.

Figure 2

Band dispersions of Tl-2212 near the Fermi surface along the cuts indicated in the upper-right panel. Data were taken at 20 K. Solid red curves are the band dispersion determined by the peak position of the momentum distribution curves (MDCs) via fitting to a Lorentzian function [3]. Blue short horizontal bars are the error bars at selected points represent the 3 $\sigma$ confidence levels from the fitted MDC peak positions. Black (white) markers are the band dispersion determined by the peak (hump) positions of representing EDCs. The bending back of the EDC-derived dispersion near $k_F$ is due to the opening of a superconducting gap. Black horizontal dashed line indicates a characteristic energy scale of the renormalization effect. Representing EDCs of A4 along the black horizontal arrow are plotted in Fig. 4b

Figure 3

Band dispersions of Tl-2201 near the Fermi surface along the cuts indicated in the upper-right panel.

Figure 4

The representing EDCs of (a) A4 for Tl-2201, (b) B4 for Tl-2212, and (d) C4 for Tl-1223 along the black arrow indicated in Figs. 2, 3, 5, respectively. (c) EDCs for Tl-2201 and Tl-1223 near ($\pi$, 0) (red point in the inset). Short vertical bars indicate the peak position. Open circles indicate the hump position. Vertical dashed lines indicate the position of the “dip.” The dashed lines in (a) and (c) are guides-to-the-eye to make the “hump” more discernible.

Figure 5

Band dispersions of Tl-1223 near the Fermi surface along the cuts indicated in the upper-right panel.