Fine structure in the tunneling spectra of electron-doped cuprates: No coupling to magnetic resonance mode

TL;DR

This study uses high-resolution tunneling spectra to identify a bosonic mode at 16 meV in electron-doped cuprates, showing it is not related to the magnetic resonance mode, thus challenging its role in high-temperature superconductivity.

Contribution

It provides evidence that the magnetic resonance mode is not responsible for superconductivity in electron-doped cuprates by analyzing spectral features and their energy scales.

Findings

Spectral fine structure indicates strong coupling to a 16 meV bosonic mode.

The bosonic mode energy is higher than the magnetic resonance mode.

Magnetic resonance mode is unlikely to be the pairing mechanism.

Abstract

We analyze high-resolution scanning tunneling spectra of the electron-doped cuprate Pr0.88LaCe0.12CuO4 (T_c = 24 K). We find that the spectral fine structure below 35 meV is consistent with strong coupling to a bosonic mode at 16 meV, in quantitative agreement with early tunneling spectra of Nd1.85Ce0.15CuO4. Since the energy of the bosonic mode is significantly higher than that (9.5-11 meV) of the magnetic resonance-like mode observed by inelastic neutron scattering, the coupling feature at 16 meV cannot arise from strong coupling to the magnetic mode. The present work thus demonstrates that the magnetic resonance-like mode cannot be the origin of high-temperature superconductivity in electron-doped cuprates.