Open AccessMagnetic relaxation in a model of interacting nanoparticles in terms of microscopic energy barriers
Author(s) -
Iglesias Òscar,
Labarta Amílcar
Publication year - 2004
Publication title -
physica status solidi (a)
Language(s) - English
Resource type - Journals
eISSN - 1521-396X
pISSN - 0031-8965
DOI - 10.1002/pssa.200405486
Subject(s) - spins , relaxation (psychology) , condensed matter physics , monte carlo method , isotropy , dipole , anisotropy energy , magnetic relaxation , anisotropy , power law , statistical physics , physics , computation , materials science , magnetic anisotropy , magnetization , magnetic field , quantum mechanics , computer science , mathematics , psychology , social psychology , statistics , algorithm
Monte Carlo simulations are used to study the magnetic relaxation of a system of single domain particles with dipolar interactions modeled by a chain of Heisenberg classical spins. We show that the so‐called T ln ( t / τ 0 ) method can be extended to interacting systems and how, from the computed master relaxation curves, the effective energy barrier distributions responsible for the relaxation can be obtained. A transition from a quasi‐logarithmic to power‐law behavior of the relaxation as the interaction strength is increased is found. By direct computation of the effective energy barriers of the system, we show that this is due to the appearance of an increasing number of small energy barriers caused by the reduction of the anisotropy energy barriers as the local dipolar fields increase. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)