Effect of on-site Coulomb repulsion on ferromagnetic fluctuations in heavily over-doped cuprates

TL;DR

This paper investigates how the decrease in on-site Coulomb repulsion with doping levels influences the emergence of ferromagnetic fluctuations in heavily overdoped cuprate superconductors, using theoretical models and advanced computational methods.

Contribution

It provides a theoretical explanation for ferromagnetic fluctuations in overdoped cuprates by linking them to doping-dependent Coulomb interactions evaluated through first-principles calculations.

Findings

On-site Coulomb interaction decreases with hole doping.

Reduced Coulomb interaction explains ferromagnetic fluctuations in overdoped cuprates.

Theoretical results align with experimental observations.

Abstract

We theoretically study ferromagnetic (FM) fluctuations that are experimentally observed in the heavily overdoped region of cuprate superconductors. To explore the origin of FM fluctuations, we evaluate the spin susceptibilities of a single-band Hubbard model within the fluctuation exchange approximation. Model parameters are derived using the Wannierization technique and the constrained random phase approximation method based on the maximally localized Wannier functions. The constrained random phase approximation calculations reveal that the on-site Coulomb interaction decreases with an increase in hole doping. By taking this reduction of the on-site Coulomb interaction into account, the emergence of FM fluctuations in heavily overdoped cuprates can be explained.