Wave Vector Difference of Magnetic Bragg Reflections and Low Energy Magnetic Excitations in Charge-stripe Ordered La2NiO4.11

M. Skoulatos,R. A. Mole,S. R. Giblin,D. Prabhakaran,P. G. Freeman

doi:10.1038/s41598-019-50904-8

Abstract

We report on the magnetism of charge-stripe ordered La2NiO4.11±0.01 by neutron scattering and μSR. On going towards zero energy transfer there is an observed wave vector offset in the centring of the magnetic excitations and magnetic Bragg reflections, meaning the excitations cannot be described as Goldstone modes of the magnetic order. Weak transverse field μSR measurements determine the magnetically order volume fraction is 87% from the two stripe twins, and the temperature evolution of the magnetic excitations is consistent with the low energy excitations coming from the magnetically ordered volume of the material. We will discuss how these results contrast with the proposed origin of a similar wave vector offset recently observed in a La-based cuprate, and possible origins of this effect in La2NiO4.11.

Highlights

A striking observation was reported on the magnetism in La2CuO4+δ (LCO+O)
A lower resolution study had previously established the presence of q-1D excitation in the same La2NiO4.11±0.01 crystal studied here[22], and the dispersion of the q-1D excitation has been observed to be doping independent in charge-stripe ordered LSNO19
To ensure that we are accounting for the presence of the q-1D excitation in La2NiO4.11±0.01, we scanned by inelastic neutron scattering the temperature dependence of magnetic excitations along (ξ, ξ, 1) at 1 meV

Summary

Introduction

A striking observation was reported on the magnetism in La2CuO4+δ (LCO+O). On going towards zero energy transfer the magnetic excitations were observed to have a different wave vector centring compared to the magnetic Bragg reflections[10], an offset. In this report we will show there is a similar offset in wave vector between the lowest energy magnetic excitations and the magnetic Bragg reflections in tetragonal charge-stripe ordered La2NiO4.11, and that these magnetic excitations have to occur in the magnetically ordered phase of the material[13,14].

Methods

Results

Discussion

Conclusion