Spin-wave dispersion in orbitally ordered La(0.5)Sr(1.5)MnO(4)

TL;DR

This study investigates magnon dispersion in La(0.5)Sr(1.5)MnO(4) using neutron scattering, revealing dominant ferromagnetic interactions and their role in phase switching between metallic and insulating states.

Contribution

It provides a detailed magnetic interaction model for La(0.5)Sr(1.5)MnO(4), highlighting the significance of ferromagnetic exchange in charge and orbital ordered phases.

Findings

Magnon dispersion matches CE-type superstructure model.

Ferromagnetic exchange dominates at high energies.

Large ferromagnetic interaction influences phase switching.

Abstract

The magnon dispersion in the charge, orbital and spin ordered phase in La(0.5)Sr(1.5)MnO(4) has been studied by means of inelastic neutron scattering. We find an excellent agreement with a magnetic interaction model basing on the CE-type superstructure. The magnetic excitations are dominated by ferromagnetic exchange parameters revealing a nearly-one dimensional character at high energies. The nearest neighbor ferromagnetic interaction in La(0.5)Sr(1.5)MnO(4) is significantly larger than the one in the metallic ferromagnetically ordered manganites. The large ferromagnetic interaction in the charge/orbital ordered phase appears to be essential for the capability of manganites to switch between metallic and insulating phases.