title: Classical and quantum magnetic phenomena in natural and artificial ferritin proteins.
abstract: 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 Néel 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.
authors.affiliation: Department of Physics, University of California, Santa Barbara 93106, USA.
authors.forename: S
authors.initials: S
authors.lastname: Gider
authors.forename: D D
authors.initials: DD
authors.lastname: Awschalom
authors.forename: T
authors.initials: T
authors.lastname: Douglas
authors.forename: S
authors.initials: S
authors.lastname: Mann
authors.forename: M
authors.initials: M
authors.lastname: Chaparala
mesh_terms: D000818:Animals; D001052:Apoferritins / Q000031:analogs & derivatives / Q000737:chemistry; D005290:Ferric Compounds; D005293:Ferritins / Q000737:chemistry*; D052203:Ferrosoferric Oxide; D006736:Horses; D007501:Iron / Q000737:chemistry; D008280:Magnetics; D008956:Models, Chemical; D010087:Oxides / Q000737:chemistry; D013696:Temperature
chemical_list: D005290:Ferric Compounds; D010087:Oxides; C088922:magnetoferritin; C092844:ferric oxyhydroxide; D005293:Ferritins; D001052:Apoferritins; D007501:Iron; D052203:Ferrosoferric Oxide