Magnetic excitations of the charge stripe electrons below half doping in La(2-x)Sr(x)NiO4, x = 0.45 and x = 0.4

TL;DR

This study investigates the magnetic excitation spectrum of charge stripe ordered La(2-x)Sr(x)NiO4 at x=0.4 and x=0.45 using neutron scattering, revealing two excitation modes and their doping evolution.

Contribution

It provides new insights into the magnetic excitations of charge stripe electrons in nickelates at different doping levels, highlighting the behavior of q-1D excitations.

Findings

Two excitation modes observed: from magnetic moments and charge stripe electrons.

The dispersion of q-1D excitations is similar to x=1/3 composition.

Spectral weight distribution differs between x=0.4 and x=0.45 samples.

Abstract

The low energy magnetic excitation spectrum of charge stripe ordered La(2-x)Sr(x)NiO4, x = 0.4 and x = 0.45 samples were studied by neutron scattering. Two excitation modes are observed in both materials, one from the ordered magnetic moments, and a second mode consistent with pseudo-one-dimensional antiferromagnetic excitations of the charge stripe electrons (q-1D). The dispersion of the q-1D excitation follows the same relation as in x = 1/3 composition, with even spectral weight in the two counter-propagating branches of the x = 0.4 sample, however in the $x = 0.45$ sample only one dispersion branch has any measurable spectral weight. The evolution of the q-1D excitations on doping to the checkerboard charge ordered phase is discussed.