Absence of an isotope effect in the magnetic resonance in high-$T_c$ superconductors

TL;DR

This study investigates the isotope effect on magnetic resonance in high-$T_c$ superconductors and finds no significant shift upon oxygen isotope substitution, indicating minimal spin-phonon coupling at optimal doping.

Contribution

It provides experimental evidence that challenges previous predictions of a notable isotope effect on magnetic resonance in high-$T_c$ cuprates.

Findings

Negligible isotope shift in magnetic resonance energy (≤ 0.2 meV).

Supports the idea of minimal spin-phonon interaction at optimal doping.

Contradicts earlier theoretical predictions of a significant isotope effect.

Abstract

An inelastic neutron scattering experiment has been performed in the high-temperature superconductor $\rm YBa_2Cu_3O_{6.89}$ to search for an oxygen-isotope shift of the well-known magnetic resonance mode at 41 meV. Contrary to a recent prediction (I. Eremin, {\it et al.}, Phys. Rev. B {\bf 69}, 094517 (2004)), a negligible shift (at best $\leq$ +0.2 meV) of the resonance energy is observed upon oxygen isotope substitution ($^{16}$O$\to^{18}$O). This suggests a negligible spin-phonon interaction in the high-$T_c$ cuprates at optimal doping.