Effects of a Collective Spin Resonance Mode on the STM Spectra of D-Wave Superconductors

TL;DR

This paper investigates how a high-energy spin resonance mode influences the local density of states in d-wave superconductors, revealing high-energy peaks and spatial modulations that can help detect and study the spin collective mode.

Contribution

It introduces a theoretical analysis of the impact of spin resonance modes on STM spectra in high-temperature superconductors, linking spin dynamics to electronic features.

Findings

High-energy peaks in LDOS due to resonance mode coupling

Two-unit-cell periodic modulation around impurities

Potential method to detect spin collective modes

Abstract

A high-energy spin resonance mode is known to exist in many high-temperature superconductors. Motivated by recent scanning tunneling microscopy (STM) experiments in superconducting Bi$_2$Sr$_2$CaCu$_2$O$_{8+\delta}$, we study the effects of this resonance mode on the local density of states (LDOS). The coupling between the electrons in a d-wave superconductor and the resonance mode produces high-energy peaks in the LDOS, which displays a two-unit-cell periodic modulation around a nonmagnetic impurity. This suggests a new means to not only detect the dynamical spin collective mode but also study its coupling to electronic excitations.