Magnetic interactions in perovskite compounds of the type La1-xSrxMO3-δ (M=3d transition such as Mn and Fe) are presumed to arise through a super exchange between 3d electrons of the magnetic ions via oxygen orbitals. The magnetic structure of La0.6Sr0.4FeO3-δ has been studied with neutron diffraction. Oxygen vacancies were created by annealing samples under various gases including N2, air and mixtures of CO/CO2. All La0.6Sr0.4FeO3-δ compounds maintain the rhombohedral structure (space group R3̄c). The air- or oxygen-annealed samples have almost no oxygen vacancies while those made in the reducing atmosphere show 7%-11% oxygen vacancies. The rhombohedral distortion decreases in the reduced samples. All the samples exhibit antiferromagnetic ordering at room temperature, although a small ferromagnetic moment may also be present. The samples with little or no oxygen vacancies show a room temperature magnetic moment of 1.4μB at the Fe site while those having > 7% oxygen vacancies show a moment of 4.0μB. Magnetization measurements reveal a much higher magnetic ordering temperature in samples with oxygen vacancies.
Z. Chu et al., "Effect of Oxygen Vacancies on the Magnetic Structure of the La₀.₆Sr₀.₄FeO3-δ Perovskite: A Neutron Diffraction Study," Journal of Applied Physics, vol. 91, American Institute of Physics (AIP), Jan 2002.
The definitive version is available at https://doi.org/10.1063/1.1455613
Materials Science and Engineering
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© 2002 American Institute of Physics (AIP), All rights reserved.
01 Jan 2002