Resonant magnetic excitations at high energy in superconducting $\bf YBa_2Cu_3O_{6.85}$

TL;DR

This study reveals new high-energy resonant magnetic excitations in the superconductor YBa2Cu3O6.85, including a 53 meV resonance and incommensurate spin excitations, enhancing understanding of spin dynamics in high-Tc superconductors.

Contribution

It reports the discovery of additional high-energy magnetic resonances in YBa2Cu3O6.85, expanding knowledge of magnetic excitations beyond the well-known 41 meV mode.

Findings

Identification of a 53 meV commensurate resonance peak

Observation of high energy incommensurate spin excitations

Spectral weight analysis consistent with electron-hole continuum

Abstract

A detailed inelastic neutron scattering study of the high temperature superconductor $\rm YBa_2Cu_3O_{6.85}$ provides evidence of new resonant magnetic features, in addition to the well known resonant mode at 41 meV: (i) a commensurate magnetic resonance peak at 53 meV with an even symmetry under exchange of two adjacent $\rm CuO_2$ layers; and (ii) high energy incommensurate resonant spin excitations whose spectral weight is around 54 meV. The locus and the spectral weight of these modes can be understood by considering the momentum shape of the electron-hole spin-flip continuum of d-wave superconductors. This provides new insight into the interplay between collective spin excitations and the continuum of electron-hole excitations.