https://doi.org/10.1007/s100510050541
Local field dynamics in a resonant quantum tunneling system of magnetic molecules
1
Centre de Recherches sur les Très Basses Températures (
laboratoire associé à l'Université J. Fourier, Grenoble.) , B.P. 166,
38042 Grenoble Cedex 9, France
2
Department of Chemistry,
University of Firenze, Via Maragliano 72, 50144 Firenze, Italy
Corresponding author: a paulsen@labs.polycnrs-gre.fr
Received:
15
May
1998
Revised:
10
July
1998
Accepted:
11
July
1998
Published online: 15 November 1998
We observed non-exponential relaxation for a quantum tunneling molecular magnetic system at very low temperatures and argue that it results from evolving intermolecular dipole fields. At the very beginning of the relaxation, the magnetization follows a square-root time dependence. A simple model is developed for the intermediate time range that is in good agreement with the data over 4 decades in time. Detailed numerical calculations as well as measurements are presented which indicate unusual correlation effects in these systems.
PACS: 75.45.+j – Macroscopic quantum phenomena in magnetic systems / 61.46.+w – Clusters, nanoparticles, and nanocrystalline materials / 75.60.Ej – Magnetization curves, hysteresis, Barkhausen and related effects
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 1998