Abstract
We have studied the magnetic dynamics in nanocrystalline hematite by inelastic neutron scattering at the high-resolution time-of-flight spectrometer IRIS at ISIS. Compared to previous inelastic neutron scattering experiments an improvement of the resolution function is achieved and more detailed information is obtained. We have performed measurements at several temperatures ranging from 5 to 325 K. The particles are canted antiferromagnetic (weakly ferromagnetic) at temperatures at least down to 5 K. We study both superparamagnetic relaxation and collective magnetic excitations of the whole particle moment at the antiferromagnetic Bragg reflection. We have studied different weightings of the particle size distribution. The data and their temperature dependence can with good agreement be interpreted on the basis of the Neel-Brown theory for superparamagnetic relaxation and a model for the collective magnetic excitations. \(C) 2003 Elsevier B.V. All rights reserved.
Original language | English |
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Journal | Journal of Magnetism and Magnetic Materials |
Volume | 266 |
Issue number | 1-2 |
Pages (from-to) | 68-78 |
ISSN | 0304-8853 |
DOIs | |
Publication status | Published - Oct 2003 |
Event | 4th International Conference on Fine Particle Magnetism - Pittsburgh, PA, United States Duration: 14 Aug 2002 → 16 Aug 2002 Conference number: 4 |
Conference
Conference | 4th International Conference on Fine Particle Magnetism |
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Number | 4 |
Country/Territory | United States |
City | Pittsburgh, PA |
Period | 14/08/2002 → 16/08/2002 |
Keywords
- magnetic fluctuations
- neutron scattering
- superparamagnetic relaxation
- hematite