Two resonant magnetic modes in an overdoped high-$\bf T_c$ superconductor

TL;DR

This study uncovers two distinct magnetic resonant modes in an overdoped high-$T_c$ superconductor, revealing new insights into its magnetic excitation spectrum and resolving a long-standing puzzle.

Contribution

It reports the first observation of an even-symmetry magnetic mode in overdoped cuprates, expanding understanding of magnetic excitations in high-$T_c$ superconductors.

Findings

Identification of two magnetic resonant modes with different symmetries.

Observation of the even mode in overdoped regime.

Spectral weight ratio provides estimates of particle-hole excitations.

Abstract

A detailed inelastic neutron scattering study of the overdoped high temperature copper oxide superconductor ${Y_{0.9}Ca_{0.1}Ba_{2}Cu_3O_{7}}$ reveals two distinct magnetic resonant modes in the superconducting state. The modes differ in their symmetry with respect to exchange between adjacent copper oxide layers. Counterparts of the mode with odd symmetry, but not the one with even symmetry, had been observed before at lower doping levels. The observation of the even mode resolves a long-standing puzzle, and the spectral weight ratio of both modes yields an estimate of the onset of particle-hole spin-flip excitations.