Development of the Magnetic Excitations of Charge-Stripe Ordered La(2-x)Sr(x)NiO(4) on Doping Towards Checkerboard Charge Order

TL;DR

This study investigates how magnetic excitations evolve in La(2-x)Sr(x)NiO(4) as doping approaches the checkerboard charge order, revealing spectrum crossover features and new ferromagnetic modes.

Contribution

It provides new insights into the magnetic excitation spectrum changes near the charge order transition in doped nickelates.

Findings

Magnetic excitation spectrum of x=0.45 matches checkerboard charge ordered La(1.5)Sr(0.5)NiO(4)

Asymmetry in magnetic excitations observed above 40 meV

Additional ferromagnetic mode found in x=0.45 but not in x=0.4

Abstract

The magnetic excitation spectrums of charge stripe ordered La(2-x)Sr(x)NiO(4) x = 0.45 and x = 0.4 were studied by inelastic neutron scattering. We found the magnetic excitation spectrum of x = 0.45 from the ordered Ni^2+ S = 1 spins to match that of checkerboard charge ordered La(1.5)Sr(0.5)NiO(4). The distinctive asymmetry in the magnetic excitations above 40 meV was observed for both doping levels, but an additional ferromagnetic mode was observed in x = 0.45 and not in the x = 0.4. We discuss the origin of crossover in the excitation spectrum between x = 0.45 and x = 0.4 with respect to discommensurations in the charge stripe structure.