Energy barriers for thermal reversal of interacting single domain particles
作者:
Wenjie Chen,
Shufeng Zhang,
H. Neal Bertram,
期刊:
Journal of Applied Physics
(AIP Available online 1992)
卷期:
Volume 71,
issue 11
页码: 5579-5584
ISSN:0021-8979
年代: 1992
DOI:10.1063/1.351376
出版商: AIP
数据来源: AIP
摘要:
An analytic solution to the energy barriers of two interacting single domain particles is presented. Identical volumes and uniaxial anisotropies are assumed with easy axes parallel to an external magnetic field. The locations and heights of the system energy barriers are analytically determined when the line joining the two particles is either parallel or perpendicular to the easy axes and the external field. The lowest energy barriers are saddle points of the energy surface and correspond to reversal modes under thermal agitation. When dipole coupling is not strong, the mode of thermal switching isasymmetricfanningorasymmetriccoherentrotation, depending upon the bond angle, rather than symmetric fanning or coherent rotation that occurs at the nucleation field. An effective volume that describes the cooperative effect is calculated and good agreement with the numerical results using the Fokker–Planck equation is obtained. The energy barriers can be used to calculate the superparamagnetic relaxation time constants in the high barrier limit.
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