Electron-Spin Excitation Coupling in an Electron Doped Copper Oxide Superconductor

TL;DR

This study reveals that in electron-doped copper oxide superconductors, antiferromagnetic spin excitations are directly linked to superconductivity, with local competition and coexistence observed at nanometer scales, highlighting electron-spin coupling as a key mechanism.

Contribution

It provides direct experimental evidence of the coupling between electron spins and superconductivity in electron-doped copper oxides using neutron scattering and tunneling spectroscopy.

Findings

Spin excitations have two distinct modes that evolve with Tc.

Antiferromagnetism and superconductivity coexist and compete on nanometer scales.

Electron-spin excitations are the dominant electron-boson coupling at low energies.

Abstract

High-temperature (high-Tc) superconductivity in the copper oxides arises from electron or hole doping of their antiferromagnetic (AF) insulating parent compounds. The evolution of the AF phase with doping and its spatial coexistence with superconductivity are governed by the nature of charge and spin correlations and provide clues to the mechanism of high-Tc superconductivity. Here we use a combined neutron scattering and scanning tunneling spectroscopy (STS) to study the Tc evolution of electron-doped superconducting Pr0.88LaCe0.12CuO4-delta obtained through the oxygen annealing process. We find that spin excitations detected by neutron scattering have two distinct modes that evolve with Tc in a remarkably similar fashion to the electron tunneling modes in STS. These results demonstrate that antiferromagnetism and superconductivity compete locally and coexist spatially on nanometer length scales, and the dominant electron-boson coupling at low energies originates from the electron-spin excitations.