Ferromagnetic in-plane spin fluctuations in NaxCoO2 observed by neutron inelastic scattering

TL;DR

This study uses neutron scattering to reveal ferromagnetic in-plane spin fluctuations in Na0.75CoO2, providing insights into magnetic excitations relevant to cobalt-oxide superconductivity.

Contribution

It provides direct experimental evidence of ferromagnetic spin fluctuations in Na0.75CoO2 using neutron inelastic scattering.

Findings

Inelastic signal at ~10 meV localized at wavevector origin

Signal is highly dispersive and decreases with temperature

Evidence supports ferromagnetic spin fluctuations in the material

Abstract

We present neutron scattering spectra taken from a single crystal of Na0.75CoO2, the precursor to a novel cobalt-oxide superconductor. The data contain a prominent inelastic signal at low energies (~10 meV), which is localized in wavevector about the origin of two-dimensional reciprocal space. The signal is highly dispersive, and decreases in intensity with increasing temperature. We interpret these observations as direct evidence for the existence of ferromagnetic spin fluctuations within the cobalt-oxygen layers.