Influence of the Third Dimension of Quasi-Two-Dimensional Cuprate Superconductors on Angle-Resolved Photoemission Spectra

TL;DR

This study investigates how the third dimension affects ARPES spectra in quasi-2D cuprate superconductors, revealing a broadening mechanism linked to interlayer hopping that impacts the interpretation of electronic properties.

Contribution

It demonstrates the influence of residual three-dimensionality on ARPES lineshapes in quasi-2D materials, providing a new spectroscopic method to detect coherent c-axis conductivity.

Findings

Interlayer hopping causes irreducible broadening in ARPES spectra.

Broadening depends on in-plane momentum $k_\parallel$.

ARPEs lineshapes can reveal c-axis coherence.

Abstract

Angle-resolved photoemission spectroscopy (ARPES) presents significant simplications in analyzing strictly two-dimensional (2D) materials, but even the most anisotropic physical systems display some residual three-dimensionality. Here we demonstrate how this third dimension manifests itself in ARPES spectra of quasi-2D materials by considering the example of the cuprate Bi$_2$Sr$_2$CaCu$_2$O$_{8}$ (Bi2212). The intercell, interlayer hopping, which is responsible for $k_z$-dispersion of the bands, is found to induce an irreducible broadening to the ARPES lineshapes with a characteristic dependence on the in-plane momentum $k_\parallel$. Our study suggests that ARPES lineshapes can provide a direct spectroscopic window for establishing the existence of coherent c-axis conductivity in a material via the detection of this new broadening mechanism, and bears on the understanding of 2D to 3D crossover and pseudogap and stripe physics in novel materials through ARPES experiments.