Effect of Nonmagnetic Impurities on the Magnetic Resonance Peak in YBa2Cu3O7

TL;DR

This study investigates how nonmagnetic Zn impurities affect the magnetic resonance peak in YBa2Cu3O7, revealing broadening and persistence of magnetic excitations above T_c, which provides insights into impurity effects on high-temperature superconductor properties.

Contribution

It provides the first detailed inelastic neutron scattering analysis of nonmagnetic impurity effects on magnetic resonance in YBa2Cu3O7, showing impurity-induced broadening and spectral weight changes.

Findings

Resonance peak broadens with Zn impurities.

Magnetic response persists above T_c.

Spectral weight increases with impurities.

Abstract

The magnetic excitation spectrum of a YBa_2 Cu_3 O_7 crystal containing 0.5% of nonmagnetic (Zn) impurities has been determined by inelastic neutron scattering. Whereas in the pure system a sharp resonance peak at E ~ 40 meV is observed exclusively below the superconducting transition temperature T_c, the magnetic response in the Zn-substituted system is broadened significantly and vanishes at a temperature much higher than T_c. The energy-integrated spectral weight observed near q = (pi,pi) increases with Zn substitution, and only about half of the spectral weight is removed at T_c.