Magnetic excitations in La$_{1.5}$Sr$_{0.5}$CoO$_4$

TL;DR

This study investigates magnetic excitations in La$_{1.5}$Sr$_{0.5}$CoO$_4$, revealing charge order, spin canting, and a spectrum of spin-wave and diffuse magnetic modes through magnetization and neutron scattering.

Contribution

First detailed analysis of magnetic excitations and charge ordering in La$_{1.5}$Sr$_{0.5}$CoO$_4$ using neutron scattering and magnetization measurements.

Findings

Charge ordering occurs below ~800K.

Spins are canted in the ab plane below ~40K.

Spin excitation spectrum includes spin waves up to 16 meV and diffuse modes around 30 meV.

Abstract

We report magnetization and neutron scattering measurements of the half-doped compound La$_{1.5}$Sr$_{0.5}$CoO$_4$, which exhibits a checkerboard pattern of charge ordering below ~800K. In the antiferromagnetically-ordered phase below \~40K the spins are found to be canted in the ab plane. The spin excitation spectrum includes spin-wave excitations with a maximum energy of 16 meV, and diffuse magnetic modes at energies around 30 meV.