Unified description of cuprate superconductors by fractionalized electrons emerging from integrated analyses of photoemission spectra and quasiparticle interference

TL;DR

This study addresses the inconsistency between ARPES and QPI results in cuprate superconductors by employing a unified theory based on the two-component fermion model ($TCFM$), where an electron fractionalizes into a quasiparticle $c$ and a hidden fermion $d$ that hybridize via $V_{oldsymbol{k}}$. By fitting ARPES data on optimally doped Bi2212, the authors determine $TCFM$ parameters and then faithfully compute QPI spectra, including the set-point–independent conductance $L(oldsymbol{q}, u)$, using a Wannier-projected Green's function and impurity scattering. The $TCFM$ reproduces both ARPES and QPI features, resolves puzzles about the ARPES–QPI dispersion mismatch, and predicts high-energy QPI signatures in the unoccupied part of the spectrum. The results support electron fractionalization arising from Mottness as a central aspect of cuprate physics and demonstrate the power of integrated spectroscopy analyses for tackling strongly correlated systems.

Abstract

Electronic structure of high-temperature superconducting cuprates is studied by analyzing experimental data independently obtained from two complementary spectroscopies, one, quasiparticle interference (QPI) measured by scanning-tunneling microscopy and the other, angle-resolved photoemission spectroscopy (ARPES) and by combining these two sets of data in a unified theoretical analysis. Through explicit calculations of experimentally measurable quantities, we show that a simple two-component fermion model (TCFM) representing electron fractionalization succeeds in reproducing various detailed features of these experimental data: ARPES and QPI data are concomitantly reproduced by the TCFM in full energy and momentum spaces. The measured QPI pattern reveals a signature characteristic of the TCFM, distinct from the conventional single-component prediction, supporting the validity of the electron fractionalization in the cuprate. The integrated analysis also solves the puzzles of ARPES and QPI data that are seemingly inconsistent with each other. The overall success of the TCFM offers a comprehensive understanding of the electronic structure of the cuprates. We further predict that a characteristic QPI pattern should appear in the unoccupied high-energy part if the fractionalization is at work. We propose that integrated-spectroscopy analyses offer a promising way to explore challenging issues of strongly correlated electron systems.

Figures (26)

• Figure 1: ARPES experimental result for the optimally-doped Bi2212 palczewski10. (a) Momentum-space map of the low-energy spectral intensity. The red solid (orange dashed) curves denote the normal-state Fermi surface (shadow band), black solid lines denote the momentum cuts along which the dispersion is measured, and the orange arrows on them denote the data used in the fitting in this study. (b) The EDCs at $\mathbf k=\mathbf k_{\rm max}$ along the cuts 5 to 13.
• Figure 2: Comparison between $\tilde{I}_{\text{ARPES}}(\mathbf k,\omega)$ and $\tilde{I}_{\text{TCFM}}(\mathbf k,\omega)$. Orange arrows denote the momentum cuts indicated in Fig. \ref{['fig:arpes']}(a).
• Figure 3: $A(\mathbf k,\omega)$ calculated for the TCFM along (a) $(0,0)-(\pi,\pi)$, (b) $(0,0)-(\pi,0)$, (c) $\mathbf k_\text{N}-\mathbf k_\text{AN}$, (d) $(0,0.5\pi)-(\pi,0.5\pi)$, (e) $(0,0.75\pi)-(\pi,0.75\pi)$, and (f) $(0,\pi)-(\pi,\pi)$. Insets to (a) and (d) illustrate the momentum cuts used in (a-f).
• Figure 4: Energy distribution curves obtained by (a) ARPES ($\tilde{I}_{\rm ARPES}$) and (b) the TCFM ($\tilde{I}_{\rm TCFM}$) at $\mathbf k=\mathbf k_{\rm max}$ in each cut.
• Figure 5: Real (blue dashed curve) and imaginary (red solid curve) parts of (a) $G$, (b) $F$, (c) $\Sigma^\text{nor}$, and (d) $\Sigma^\text{ano}$ at the antinode, $\mathbf k=\mathbf k_\text{AN}=(\pi,0.14\pi)$, calculated by the fitted TCFM.