Charge order driven by Fermi-arc instability in Bi2201 (1312.1343v2)

Abstract: The understanding of the origin of superconductivity in cuprates has been hindered by the apparent diversity of intertwining electronic orders in these materials. We combined resonant x-ray scattering (REXS), scanning-tunneling microscopy (STM), and angle-resolved photoemission spectroscopy (ARPES) to observe a charge order that appears consistently in surface and bulk, and in momentum and real space within one cuprate family, Bi2201. The observed wave vectors rule out simple antinodal nesting in the single-particle limit but match well with a phenomenological model of a many-body instability of the Fermi arcs. Combined with earlier observations of electronic order in other cuprate families, these findings suggest the existence of a generic charge-ordered state in underdoped cuprates and uncover its intimate connection to the pseudogap regime.

• The paper demonstrates that charge order in Bi2201 is driven by Fermi-arc instability, established through a combined use of REXS, STM, and ARPES techniques.
• It finds that the charge ordering wavevector aligns with the Fermi arc tips rather than the antinodal segments, challenging conventional nesting hypotheses.
• The study links the onset of charge order just below T* with pseudogap behavior, offering new insights into the electronic instabilities of underdoped cuprates.

Charge Order and Fermi-Arc Instability in Bi$_2$Sr$_{2-x}$La$_{x}$CuO$_{6+\delta}$ Cuprate Superconductors

The paper presents a detailed paper of charge order phenomena in the superconducting cuprate material Bi$_2$Sr$_{2-x}$La$_{x}$CuO$_{6+\delta}$ (Bi2201), elucidating key aspects of its electronic structure and fermiology. Leveraging resonant X-ray scattering (REXS), scanning tunneling microscopy (STM), and angle-resolved photoemission spectroscopy (ARPES), the paper identifies a consistent charge order across multiple experimental techniques and both surface and bulk states. This research highlights the presence of a generic charge-ordered state in underdoped cuprates and connects it to the pseudogap regime.

Core Findings and Methodology

The investigation discovers a charge ordering wavevector that is congruent with the tips of the Fermi arcs rather than the antinodal segments of the Fermi surface. This directly challenges previous hypotheses that antinodal nesting plays a central role in the pseudogap state's charge ordering. Observations of the charge order onset coinciding with the pseudogap temperature (${T}^{*}$) further suggest an intimate relationship between these electronic phenomena.

The research utilized a combination of resonant X-ray scattering at specific absorption edges to enhance sensitivity towards electronic charges in the CuO$_2$ layers, STM to map electronic states at the surface, and ARPES to detail the band structure and Fermi surface topology. Specifically, REXS measurements show that the charge order emerges just below ${T}^{*}$ with an ordering wavevector aligning with the Fermi arc tips. Complementary STM data reveal a modulation consistent with the bulk findings, and ARPES highlights the transformation of the Fermi surface under the influence of the pseudogap.

The paper notably departs from conventional explanations of charge ordering in terms of simple Peierls-like charge-density-waves. Instead, it proposes that the peculiar Fermi surface topology in the pseudogap state, characterized by disconnected Fermi arcs, underpins the observed charge order. Modeling approaches that involve incorporating self-energy effects to capture the pseudogap behavior demonstrate that the interacting Fermi arc tips' momentum aligns well with the observed charge order vector.

Implications and Future Directions

This paper has implications for understanding the electronic instabilities in cuprate superconductors, suggesting that charge ordering should be viewed in the more complex context of the pseudogap-specified fermiology rather than simplified nesting concepts. Furthermore, by linking a many-body instability within the Fermi arcs to generic charge order in underdoped cuprates, it provides a refined framework to consider how pseudogap dynamics influence superconductivity.

Future research could benefit from extending this multimodal approach to other cuprate and related high-temperature superconductors, hence broadening the understanding of universal behaviors across this class of materials. Similarly, theoretical advancements could incorporate these insights into more sophisticated models that consider correlations and interactions beyond current phenomenological descriptions. Potential areas for exploration include the role of other competing orders and investigating how changes in doping levels influence the complex interplay between pseudogap formation, charge order instabilities, and eventual superconductivity.

In summary, this paper offers a rigorous examination of charge order phenomena in Bi2201 cuprates through a robust, multimodal investigative approach. It highlights the nuanced interplay between charge order and fermiology in the pseudogap regime, providing critical insights that advance the discourse on high-temperature superconductivity.