Shadow bands, gap and pseudogaps in high-T_c superconductors

TL;DR

This paper presents a model based on charge density wave quantum criticality that explains key features of the Fermi surface, spectral weight transfer, and d-wave superconducting gap in high-T_c superconductors, aligning with experimental observations.

Contribution

The paper introduces a novel model coupling electrons to quasi-critical fluctuations within the CDW-QCP framework, capturing experimental Fermi surface features and superconducting gap symmetry.

Findings

Reproduces ARPES Fermi surface features in optimally doped Bi2212.

Shows spectral weight transfer to shadow peaks and formation of shadow Fermi surfaces.

Demonstrates d-wave gap symmetry arising from charge and spin fluctuation interplay.

Abstract

Within the framework of the Charge Density Wave Quantum Critical Point (CDW-QCP) scenario for high-T_c superconductors (HTCS), we introduce a model for tight-binding electrons coupled to quasi-critical fluctuations. In the normal state our model reproduces features of the Fermi Surface (FS) observed in ARPES measurements on optimally doped Bi2212, such as the anisotropic suppression of spectral weight around the M points of the Brillouin zone. The spectral density is characterized by a transfer of spectral weight from the main quasi-particle peak to dispersing shadow peaks which originate branches of a shadow FS. In the superconducting state our model reproduces the d-wave symmetry of the gap parameter, which results from a balance between small-q attraction and large-q repulsion. The gap parameter is enhanced due to cooperative effects of charge and spin fluctuations.