Phenomenological BCS theory of the high-$T_c$ cuprates

TL;DR

This paper presents a phenomenological BCS model with specific pairing interactions and empirical dispersion to explain the superconducting pair state in hole-doped cuprates, emphasizing flat bands, small on-site repulsion, and dominant next-nearest neighbor attraction.

Contribution

It introduces a BCS framework incorporating empirical dispersion and specific interaction parameters to explain high-$T_c$ cuprate superconductivity.

Findings

Flat bands are essential for pairing.

Small on-site repulsion facilitates pairing.

Next-nearest neighbor attraction dominates the pairing mechanism.

Abstract

A BCS model characterized by a phenomenological pair potential with on-site ($V_0$), nearest ($V_1$), and next nearest ($V_2$) neighbour coupling constants, and an empirical quasiparticle dispersion taken from angle-resolved photoemission spectra is considered. The model can consistently explain the experimental data concerning the pair state of the hole doped cuprates. Three ingredients are required to make the interpretation possible: the existence of flat bands, a very small effective on-site repulsion, and a slightly dominating effective nnn attraction $V_2$ of the order of 60-80meV with a ratio $V_2/V_1 \approx 1.5$.