title: Sensing the quantum behaviour of magnetic nanoparticles by electron magnetic resonance.
abstract: We have investigated Magnetic Nanoparticles (MNPs) of spinel type iron oxide (of approximately 8 nm) mineralized in the internal cavity of the bioreactor ferritin nanocage. In particular, we have used Electron Magnetic Resonance, EMR, spectroscopy and taken advantage of the capacity of the protein shells to control the size of the MNPs. EMR measurements in perpendicular and parallel configurations have been recorded at various temperatures. A model based on the giant spin is used to interpret the experimental results. The analysis indicates that the observed quantum behaviour has to be ascribed to the whole MNP and that the thermal population of excited spin states has a strong influence in the EMR behaviour of MNPs.
authors.affiliation: INSTM and Department of Physics and Astronomy, University of Florence, via Sansone 1, 50019 Sesto Fiorentino, Italy. maria.fittipaldi@unifi.it.
authors.forename: M
authors.initials: M
authors.lastname: Fittipaldi
authors.affiliation: INSTM and Department of Physics and Astronomy, University of Florence, via Sansone 1, 50019 Sesto Fiorentino, Italy. maria.fittipaldi@unifi.it.
authors.forename: R
authors.initials: R
authors.lastname: Mercatelli
authors.affiliation: INSTM and Department of Chemistry "U. Schiff", University of Florence, via della Lastruccia, 3-13 50019 Sesto Fiorentino, Italy.
authors.forename: S
authors.initials: S
authors.lastname: Sottini
authors.affiliation: CNR, Institute of Molecular Biology and Pathology, 00185 Rome, Italy.
authors.forename: P
authors.initials: P
authors.lastname: Ceci
authors.affiliation: CNR, Institute of Molecular Biology and Pathology, 00185 Rome, Italy and Department of Biochemical Sciences "A. Rossi Fanelli", University "Sapienza", Rome, Italy.
authors.forename: E
authors.initials: E
authors.lastname: Falvo
authors.affiliation: INSTM and Department of Chemistry "U. Schiff", University of Florence, via della Lastruccia, 3-13 50019 Sesto Fiorentino, Italy.
authors.forename: D
authors.initials: D
authors.lastname: Gatteschi