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Science 7 April 1995:
Vol. 268. no. 5207, pp. 77 - 80
DOI: 10.1126/science.7701343
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Articles

Science, Vol 268, Issue 5207, 77-80
Copyright © 1995 by American Association for the Advancement of Science

articles

Classical and quantum magnetic phenomena in natural and artificial ferritin proteins

S Gider, DD Awschalom, T Douglas, S Mann, and M Chaparala

Department of Physics, University of California, Santa Barbara 93106, USA.

Artificial ferritin has been synthesized with control of both the magnetic state (antiferromagnetic or ferrimagnetic) and the particle size over an ofer of magnitude in the number of iron atoms. The magnetic properties of the artificial ferritin were compared with those of natural horse spleen ferritin in a range of temperatures (20 millikelvin to 300 kelvin) and fields (1 nanotesla to 27 tesla). In the classical regime, the blocking temperature was found to correlate with the average particle size. A correlation was also observed in the quantum regime between the resonance frequency of macroscopic quantum tunneling of the Neel vector and the particle size. At high magnetic fields (to 27 tesla), a spin flop transition with a strong dependence on orientation was seen in the natural ferritin, providing evidence of antiferromagnetism in this system.


THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES:
Mineralogy of a natural As-rich hydrous ferric oxide coprecipitate formed by mixing of hydrothermal fluid and seawater: Implications regarding surface complexation and color banding in ferrihydrite deposits.
D. G. Rancourt, D. Fortin, T. Pichler, P.-J. Thibault, G. Lamarche, R. V. Morris, and P. H.J. Mercier (2001)
American Mineralogist 86, 834-851
   Abstract »    Full Text »    PDF »
Response: Does Macroscopic Quantum Coherence Occur in Ferritin?.
S. Gider, D. D. Awschalom, D. P. DiVincenzo, and D. Loss (1996)
Science 272, 425-426
   PDF »


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