Ferromagnetic Excitations in La$_{0.82}$Sr$_{0.18}$CoO$_{3}$ Observed Using Neutron Inelastic Scattering

TL;DR

This study uses polarized neutron scattering to investigate ferromagnetic spin excitations in La$_{0.82}$Sr$_{0.18}$CoO$_{3}$, revealing well-defined magnons at low energies and damping at higher energies, with implications for magnetic interactions.

Contribution

First detailed measurement of spin excitations in La$_{0.82}$Sr$_{0.18}$CoO$_{3}$ using neutron scattering, providing insights into magnon behavior and damping mechanisms.

Findings

Magnon spectrum is well defined at low energies

Magnons become heavily damped at higher energies

Spin wave stiffness constant is $D=94\,\pm 3$ meV Å$^{2}$

Abstract

Polarized neutron inelastic scattering has been used to measure spin excitations in ferromagnetic La$_{0.82}$Sr$_{0.18}$CoO$_{3}$. The magnon spectrum of these spin excitations is well defined at low energies but becomes heavily damped at higher energies, and can be modeled using a quadratic dispersion. We determined a spin wave stiffness constant of $D=94\pm 3$\,meV\,\AA$^{2}$. Assuming a nearest-neighbor Heisenberg model we find reasonable agreement between the exchange determined from D and the bulk Curie temperature. Several possible mechanisms to account for the observed spin-wave damping are discussed.