https://doi.org/10.1140/epjb/e2005-00396-7
Square root relaxation: two possible mechanisms
Département de Recherche Fondamentale sur la Matière
Condensée D.S.M., Commissariat à l'Énergie Atomique, 17 Avenue des Martyrs, 38054 Grenoble Cedex 9, France
Corresponding author: a jvillain@cea.fr
Received:
19
January
2005
Revised:
23
June
2005
Published online:
16
December
2005
Magnetic relaxation in large spin molecular paramagnets is often found to behave as
at short times t. This behaviour was
explained by Prokofiev & Stamp as arising from dipole interactions between molecular spins.
However, as observed by Miyashita & Saito, the same behaviour can arise from
a different mechanism which, in the present work, is related to hyperfine interactions.
The Miyashita-Saito scheme is found to be possible
at short times if the nuclear longitudinal
spin relaxation is very slow. In the case of moderately slow nuclear
spin relaxation, the electronic magnetization variation 
is initially proportional to t, then to 
and finally to 
.
This behaviour may be mostly expected in dilute systems.
PACS: 05.30.-d – Quantum statistical mechanics / 05.40.Fb – Random walks and Levy flights / 75.50.Xx – Molecular magnets
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 2005
