Identifying Collective Modes via Impurities in the Cuprate Superconductors

TL;DR

This paper demonstrates how impurities in cuprate superconductors can be used to distinguish between collective charge and spin modes by analyzing their unique effects on the local density of states, aiding in understanding their fundamental properties.

Contribution

The study introduces impurity-based probes to differentiate collective charge and spin modes in cuprate superconductors through their distinct signatures in the local density of states.

Findings

Resonant impurity state creation is suppressed in spin droplets.

Spin-resolved LDOS shows characteristic spatial patterns.

LDOS changes significantly with magnetic field in spin droplets.

Abstract

We show that the pinning of collective charge and spin modes by impurities in the cuprate superconductors leads to qualitatively different fingerprints in the local density of states (LDOS). In particular, in a pinned (static) spin droplet, the creation of a resonant impurity state is suppressed, the spin-resolved LDOS exhibits a characteristic spatial pattern, and the LDOS undergoes significant changes with increasing magnetic field. Since all of these fingerprints are absent in a charge droplet, impurities are a new probe for identifying the nature and relative strength of collective modes.