Cooperative localization-delocalization in the high Tc cuprates

TL;DR

This paper explores how the intrinsic metastable crystal structure of high Tc cuprates causes local lattice instabilities, leading to a coexistence of localized and delocalized electronic features, and influences their superconducting properties.

Contribution

It introduces a model linking local lattice instabilities and heterogeneity to the partial Fermi surface fractioning and dynamical pairing in high Tc cuprates.

Findings

Partial Fermi surface hidden around anti-nodal points due to pseudogap.

Segregation into checker-board nano-structures causes localized high-energy features.

Dynamical pairing arises from charge carriers trapped in fluctuating environments.

Abstract

The intrinsic metastable crystal structure of the cuprates results in local dynamical lattice instabilities, strongly coupled to the density fluctuations of the charge carriers. They acquire in this way simultaneously both, delocalized and localized features. It is responsible for a partial fractioning of the Fermi surface, i.e., the Fermi surface gets hidden in a region around the anti-nodal points, because of the opening of a pseudogap in the normal state, arising from a partial charge localization. The high energy localized single-particle features are a result of a segregation of the homogeneous crystal structure into checker-board local nano-size structures, which breaks the local translational and rotational symmetry. The pairing in such a system is dynamical rather than static, whereby charge carriers get momentarily trapped into pairs in a deformable dynamically fluctuating ligand environment. We conclude that the intrinsically heterogeneous structure of the cuprates must play an important role in this type of superconductivity.