2000/07/06 by C. Gilles, Gilles, C., P. Bonville +5
Earth and Planetary Sciences · Engineering · Medicine · Physics and Astronomy · #Characterization and Applications of Magnetic Nanoparticles #FOS: Physical sciences #Iron Metabolism and Disorders #Materials Science (cond-mat.mtrl-sci) #Mesoscale and Nanoscale Physics (cond-mat.mes-hall) #cond-mat.mes-hall #cond-mat.mtrl-sci #nanoparticles nucleation surface interactions
paper · pdf · doi:10.48550/arxiv.cond-mat/0007087
11 pages, 11 figures
openalex publication_date 2000/07/06 · arxiv created 2000/08/23 · arxiv updated 2009/11/30 · openalex created_date 2022/08/29 · openalex updated_date 2026/07/28
The magnetic behaviour of nanoparticles of antiferromagnetic ferritin has been investigated by 57Fe Mossbauer absorption spectroscopy and magnetisation measurements, in the temperature range 2.5K-250K and with magnetic fields up to 7T. Samples containing nanoparticles with an average number of Fe atoms ranging from 400 to 2500 were studied. The value of the anisotropy energy per unit volume was determined and found to be in the range 3-6 10**5 ergs/cm3, which is a value typical for ferric oxides. By comparing the results of the two experimental methods at large field, we show that, contratry to what is currently assumed, the uncompensated magnetisation of the feritin cores in the superparamagnetic regime does not follow a Langevin law. For magnetic fields below the spin-flop field, we propose an approximate law for the field and temperature variation of the uncompensated magnetisation which has so far never been applied in antiferromagnetic systems. This approach should more generally hold for randomly oriented antiferro- magnetic nanoparticles systems with weak uncompensated moments.