Nd ordering, cluster formation, and the origin of negative magnetization in NdMn0.8Fe0.2O3+δ

•Neodymium ordering is quantified, clarifying the magnetic structure and phase transitions.•Magnetic clusters are observed in neutron diffraction.•A model for negative magnetization is presented. The orthorhombic pseudo-perovskite series NdMn1-xFexO3+δ has negative magnetization, i.e. magnetization...

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Bibliographic Details
Published in:Journal of magnetism and magnetic materials 2020-03, Vol.497 (C), p.165968, Article 165968
Main Authors: Pajerowski, D.M., Escanhoela, C.A., Haskel, D., Prisk, T.R., Frontzek, M.D., Phelan, D., Mihalik, M.
Format: Article
Language:English
Subjects:
Backscattering
Clusters
Dichroism
Elastic scattering
Freezing
Inelastic scattering
Long range order
Magnetic domains
Magnetism
Magnetization
MATERIALS SCIENCE
Neutron diffraction
Neutron scattering
Neutrons
Perovskites
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Summary:•Neodymium ordering is quantified, clarifying the magnetic structure and phase transitions.•Magnetic clusters are observed in neutron diffraction.•A model for negative magnetization is presented. The orthorhombic pseudo-perovskite series NdMn1-xFexO3+δ has negative magnetization, i.e. magnetization directed opposite to an applied field under certain conditions, for x = 0.2 and x = 0.25. We have investigated the microscopic origin of this phenomenon for x = 0.2 by using elastic and inelastic scattering techniques including neutron backscattering, X-ray magnetic circular dichroism at the Mn K and Nd L2 edges, neutron powder diffraction, and powder inelastic neutron scattering. We find that Nd3+ ions possess zero field ordered moments of 1.6 μB per ion at 1.5 K oriented parallel to the Mn moments. Based upon the neutron diffraction, there is a freezing of magnetic clusters before the long-range order sets in. The Nd crystal field levels shift with temperature due to a molecular field that is 1.1 meV at 1.5 K. These findings are consistent with a magnetic domain/cluster model for the negative magnetization in NdMn0.8Fe0.2O3+δ.
ISSN:0304-8853
1873-4766
DOI:10.1016/j.jmmm.2019.165968