Eur. Phys. J. B 6, 195-199 (1998)
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

Abstract

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.