Magnetic Properties of Mn-Doped Amorphous SiO_2 Matrix

• Authors: D. Milivojević , B. Babić-Stojić , V. Jokanović , Z. Jagličić , D. Makovec
• Languages of publication: EN

Abstracts

EN

Samples of Mn-doped amorphous SiO_2 matrix with manganese concentration 0.7 and 3 at.% have been prepared by a sol-gel method. Transmission electron microscopy analysis has shown that the samples contain agglomerates of amorphous silica particles 10 - 20 nm in size. Two types of Mn-rich particles are dispersed in silica matrix, smaller nanoparticles with dimensions between 3 and 10 nm, and larger crystalline areas consisting of aggregates of the smaller nanoparticles. High-temperature magnetic susceptibility reveals that dominant magnetic phase at higher temperatures is λ-MnO_2. At temperatures below T_{C}=43 K strong ferrimagnetism originating from the minor Mn_3O_4 phase masks the relatively weak magnetism of λ-MnO_2. Magnetic field dependence of the maximum in the zero-field-cooled magnetization for both the samples in the vicinity of 40 K, and a frequency shift of the real component of the AC magnetic susceptibility in the sample with 3 at.% Mn suggest that the magnetic moments of the smaller Mn_3O_4 nanoparticles with dimensions below 10 nm are subject to thermally activated blocking process just below the Curie temperature T_{C}. The low-temperature maximum in the zero-field-cooled magnetization observed for both the samples below 10 K indicates possible spin glass freezing of the magnetic moments in the geometrically frustrated Mn sublattice of the λ-MnO_2 crystal structure.

Keywords

EN

75.50.Lk; 75.47.Lx; 75.50.Tt

Discipline

• 75.50.Tt: Fine-particle systems; nanocrystalline materials
• 75.47.Lx: Magnetic oxides
• 75.50.Lk: Spin glasses and other random magnets

• Journal: Acta Physica Polonica A
• Year: 2011
• Volume: 120
• Issue: 2
• Pages: 316-321

Dates

published

2011-08

Contributors

author

D. Milivojević

• Vinča Institute of Nuclear Sciences, University of Belgrade, P.O.Box 522, 11001 Belgrade, Serbia

author

B. Babić-Stojić

• Vinča Institute of Nuclear Sciences, University of Belgrade, P.O.Box 522, 11001 Belgrade, Serbia

author

V. Jokanović

• Vinča Institute of Nuclear Sciences, University of Belgrade, P.O.Box 522, 11001 Belgrade, Serbia

author

Z. Jagličić

• Institute of Mathematics, Physics and Mechanics, Jadranska 19, 1000 Ljubljana, Slovenia

author

D. Makovec

• Jožef Stefan Institute, Department for Materials Synthesis, Jamova 39, 1000 Ljubljana, Slovenia

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Identifiers

DOI

10.12693/APhysPolA.120.316