Superconductivity-Induced Anomalies in the Spin Excitation Spectra of Underdoped YBa_2 Cu_3 O_{6+x}

TL;DR

This study uses neutron scattering to reveal how superconductivity affects magnetic excitation spectra in underdoped YBa2Cu3O6+x, showing energy-specific spectral weight changes linked to the magnetic resonance peak.

Contribution

It provides new insights into the superconductivity-induced anomalies in magnetic spectra of underdoped YBa2Cu3O6+x using neutron scattering techniques.

Findings

Spectral weight enhancements at 25 meV and 33 meV below T_c.

Compensatory spectral weight loss at higher energies.

Clues to the origin of the 40 meV magnetic resonance peak.

Abstract

Polarized and unpolarized neutron scattering has been used to determine the effect of superconductivity on the magnetic excitation spectra of YBa_2 Cu_3 O_{6.5} (T_c = 52K) and YBa_2 Cu_3 O_{6.7} (T_c = 67K). Pronounced enhancements of the spectral weight centered around 25 meV and 33 meV, respectively, are observed below T_c in both crystals, compensated predominantly by a loss of spectral weight at higher energies. The data provide important clues to the origin of the 40 meV magnetic resonance peak in YBa_2 Cu_3 O_7.