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

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

doi:10.1038/s41598-019-50904-8

Wave Vector Difference of Magnetic Bragg Reflections and Low Energy Magnetic Excitations in Charge-stripe Ordered La₂NiO_4.11

Sci Rep. 2019 Oct 8;9(1):14468. doi: 10.1038/s41598-019-50904-8.

Authors

P G Freeman^{1

2}, S R Giblin³, M Skoulatos^{4

5}, R A Mole^{6

7}, D Prabhakaran⁸

Affiliations

¹ Jeremiah Horrocks Institute for Mathematics, Physics, and Astronomy, University of Central Lancashire, Preston, PR1 2HE, UK. pgfreeman@uclan.ac.uk.
² Laboratory for Quantum Magnetism, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015, Lausanne, Switzerland. pgfreeman@uclan.ac.uk.
³ Cardiff School of Physics and Astronomy, Queens Building, The Parade, Cardiff University, Cardiff, CF24 3AA, UK.
⁴ Laboratory for Neutron Scattering, Paul Scherrer Institute, Villigen PSI, Villigen, Switzerland.
⁵ Physik Department E21, Technische Universität München, James-Franck-Str., 85747, Garching, Germany.
⁶ Heinz Maier-Leibnitz Zentrum, Lichtenbergstraße, 1, 85747, Garching, Germany.
⁷ Australian Nuclear Science and Technology Organisation, New Illawarra Rd, Lucas Heights, NSW, Australia.
⁸ Department of Physics, Clarendon Laboratory, Oxford University, Oxford, OX1 3PU, UK.

Abstract

We report on the magnetism of charge-stripe ordered La₂NiO_4.11±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 La₂NiO_4.11.