Effects of impurities and vortices on the low-energy spin excitations in high-Tc materials

TL;DR

This paper reviews how impurities and vortices influence low-energy spin excitations in high-Tc cuprates, highlighting the role of disorder in inducing magnetic phases and affecting spin dynamics, consistent with experimental observations.

Contribution

It presents a theoretical framework explaining how disorder in a d-wave superconductor leads to magnetic phases and modifies spin excitations, aligning with experimental data.

Findings

Disorder induces local antiferromagnetic droplets in cuprates.

Disorder and magnetic fields slow down spin fluctuations.

Theoretical results match neutron scattering and muSR experiments.

Abstract

We review a theoretical scenario for the origin of the spin-glass phase of underdoped cuprate materials. In particular it is shown how disorder in a correlated d-wave superconductor generates a magnetic phase by inducing local droplets of antiferromagnetic order which eventually merge and form a quasi-long range ordered state. When correlations are sufficiently strong, disorder is unimportant for the generation of static magnetism but plays an additional role of pinning disordered stripe configurations. We calculate the spin excitations in a disordered spin-density wave phase, and show how disorder and/or applied magnetic fields lead to a slowing down of the dynamical spin fluctuations in agreement with neutron scattering and muon spin rotation (muSR) experiments.