Magnon Damping by magnon-phonon coupling in Manganese Perovskites

TL;DR

This study uses inelastic neutron scattering to reveal that strong magneto-elastic coupling causes magnon damping and anomalous spin dynamics in ferromagnetic manganese perovskites, regardless of their Curie temperatures.

Contribution

It demonstrates that magnon-phonon coupling explains the low-temperature spin dynamical anomalies in manganese perovskites.

Findings

Magnon damping correlates with optical phonon modes.

Similar spin wave dispersions across different Curie temperatures.

Magneto-elastic coupling causes observed magnon damping.

Abstract

Inelastic neutron scattering was used to systematically investigate the spin-wave excitations (magnons) in ferromagnetic manganese perovskites. In spite of the large differences in the Curie temperatures ($T_C$s) of different manganites, their low-temperature spin waves were found to have very similar dispersions with the zone boundary magnon softening. From the wavevector dependence of the magnon lifetime effects and its correlation with the dispersions of the optical phonon modes, we argue that a strong magneto-elastic coupling is responsible for the observed low temperature anomalous spin dynamical behavior of the manganites.