Disorder-Induced Static Antiferromagnetism in Cuprate Superconductors

TL;DR

This paper demonstrates through model calculations that dopant disorder can induce static antiferromagnetic order in cuprate superconductors, explaining experimental observations of magnetic components in disordered samples.

Contribution

It reveals how disorder stabilizes antiferromagnetic states in cuprates, reducing the correlation strength needed for magnetic order compared to isolated droplets.

Findings

Disorder lowers the threshold for magnetic order formation.

Static magnetic components are present in disordered cuprates like LSCO.

Clean samples like YBCO show minimal or no magnetic order.

Abstract

Using model calculations of a disordered d-wave superconductor with on-site Hubbard repulsion, we show how dopant disorder can stabilize novel states with antiferromagnetic order. We find that the critical strength of correlations or impurity potential necessary to create an ordered magnetic state in the presence of finite disorder is reduced compared to that required to create a single isolated magnetic droplet. This may explain why in cuprates like LSCO low-energy probes have identified a static magnetic component which persists well into the superconducting state, whereas in cleaner systems like YBCO it is absent or minimal. Finally we address the case of nominally clean LSCO samples at optimal doping, where such ordered magnetic moments are absent, but where they can be induced by small concentrations of strong scatterers.