Title:
Characterization of the low-energy bosonic modes in Bi2Sr2CaCu2O8+x with incipient charge order
Abstract:
Cuprate high-temperature superconductors have been studied intensely for the past 30 years, understanding the mechanism responsible for superconductivity remains a significant challenge in condensed matter physics. Developing this understanding requires knowledge of both the fermionic charge excitations and many-body bosonic interactions that drive the associated emergent phenomena. Through work done through the Center for Emergent Superconductivity (CES), we have developed the technique of momentum-resolved electron energy-loss spectroscopy (M-EELS). M-EELS is capable of performing a full momentum-space mapping of the low-energy bosonic degrees of freedom over the first Brillouin zone with meV energy resolution, allowing us to characterize the interactions that give rise to collective electron dynamics. We present a study of the high-temperature superconductor material Bi2Sr2CaCu2O8+x (Bi2212) using M-EELS to measure low-energy electron dynamics. In optimally doped Bi2212, we find the emergence of static, short-range charge order at low temperature. The full measurement of χ"(q,ω) shows low-energy charge excitations, and resolving these excitations in momentum space, we see these excitations carry a similar structure to the charge order, suggesting that the static electronic order modulates the many-body interaction. We show that this observation is qualitatively consistent with features observed in the single particle spectral function by ARPES, namely the nodal dispersion anomaly, or “kink”.
