Through a Lattice Darkly: Shedding Light on Electron–Phonon Coupling in the High-T_c Cuprates

Abstract

With its central role in conventional BCS superconductivity, electron-phonon coupling has appeared to play a more subtle role in the phase diagram of the high temperature superconducting cuprates. The added complexity of the cuprates with potentially numerous competing phases including charge, spin, orbital, and lattice ordering, makes teasing out any unique phenomena challenging. In this review, we present our work using angle resolved photoemission spectroscopy (ARPES) to explore the role of the lattice and its effect on the valence band electronic structure in the cuprates. We provide an introduction to the ARPES technique and its unique ability to the probe the effect of bosonic renormalization (or "kink") on the near-EF band structure. Our survey begins with the establishment of the ubiquitous nodal cuprate kink leading to the way isotope substitution has shed a critical new perspective on the role and strength of electron-phonon coupling. We continue with recently published work on the connection between the phonon dispersion as seen with inelastic x-ray scattering (IXS) and the location of the kink as observed by ARPES near the nodal point. Finally, we present very recent and ongoing ARPES work examining how induced strain through chemical pressure provides a potentially promising avenue for understanding the broader role of the lattice to the superconducting phase and larger cuprate phase diagram.

Translational-Invariant Bipolarons and Superconductivity

“…Hence the quantity |E B |/2 will play the role of a pseudogap in one-particle transitions, while |E B | plays the role of a pseudogap in two-particle transitions. This conclusion is in full agreement with numerous tunnel experiments in HTSC [178,182,183].…”

“…The dependence E(k) shown in Figure 15 corresponds to ARPES observations of kinks in a lot of HTSC materials (see, for example review [178]). For example, according to [178] in the well-studied cuprate Bi2212 the kink energy (| |/2) is 70 meV.…”

“…Angle Resolved Photo Electron Spectroscopy (ARPES). Apart from STM, a direct method providing information on the properties of a superconducting gap is angle resolved photo electron The dependence E(k) shown in Figure 15 corresponds to ARPES observations of kinks in a lot of HTSC materials (see, for example review [178]). For example, according to [178] in the well-studied cuprate Bi2212 the kink energy (|E B |/2) is 70 meV.…”

Deep learning-based statistical noise reduction for multidimensional spectral data

“…The fitting results of LC + NN and HC data are almost identical, directly demonstrating that the denoising neural network preserves the quantitative information of the band structure. We wish to point out that the well-known 70 meV kink at the nodal point is clearly resolved for both LC + NN and HC data 29,30 , whereas the fitting result of the raw LC data is too noisy to identify the kink position.…”

Translational-invariant bipolarons and superconductivity

“…Приведённая на рис. зависимость E(k) соответствует ARPES наблюдениям кинков в большом числе ВТСП материалов (см., например, обзор[172]). Так, например, согласно[172] в хорошо изученном купрате Bi2212 энергия кинка (…”