Superconductivity Induced by Negative Centers

TL;DR

This paper investigates how random distribution of attractive centers in a generalized negative U Hubbard model induces superconductivity, revealing the critical concentration needed and the local density evolution that leads to global coherence.

Contribution

It introduces a study of superconductivity emergence in a disordered negative U Hubbard model using quantum Monte Carlo simulations, identifying the critical concentration of negative centers.

Findings

Superconductivity occurs above a critical concentration of negative centers.

Local density variations provide insight into phase coherence formation.

The study quantifies the relationship between disorder and superconducting transition.

Abstract

We study the effect of random dilution of attraction centers on electron pairing in a generalization of the negative $U$ Hubbard model where the interaction $U_i$, defined on the two dimensional lattice, can be $-|U|$ and 0 with probability $c$ and $1-c$ depending on the lattice site $i$. Using the determinant quantum Monte Carlo approach, we find the critical concentration $c_0$ of negative centers which leads to superconductivity, and show how the evolution of the local density on the two types of sites lends insight into the formation of global phase coherence.