Magnetic Instability in Strongly Correlated Superconductors

TL;DR

This paper investigates a new model for strongly correlated superconductors, showing that increasing electron repulsion near half-filling leads to a transition from superconductivity to antiferromagnetic insulator.

Contribution

It introduces the Gossamer Hamiltonian as a model for cuprates with strong Coulomb repulsion and analyzes its instability towards antiferromagnetic insulator phases.

Findings

Superconducting state becomes unstable near half-filling with strong repulsion.

Quantum phase transition from superconductor to antiferromagnetic insulator.

Increased Coulomb repulsion induces magnetic ordering.

Abstract

Recently a new phenomenological Hamiltonian has been proposed to describe the superconducting cuprates. This so-called Gossamer Hamiltonian is an apt model for a superconductor with strong on-site Coulomb repulsion betweenthe electrons. It is shown that as one approaches half-filling the Gossamer superconductor, and hence the superconducting state, with strong repulsion is unstable toward an antiferromagnetic insulator an can undergo a quantum phase transition to such an insulator if one increases the on-site Coulomb repulsion.