Uniaxial anisotropy single-domain particles, relaxation

Sanchez et al. presented a computer simulation of the magnetic relaxation of an assembly of nonidentical, noninteracting, single-domain particles with uniaxial anisotropy. They analyzed the dependence of the magnetic viscosity dMIdXnt) on the shape of the energy barrier distribution function, assumed to be lognormal in type. 

In this section we consider the dependence of the relaxation time on the internal anisotropy of a single domain ferromagnetic particle. Thus it is applicable only to Neel relaxation. We consider the simplest form of anisotropy, namely uniaxial anisotropy described by the potential... 

Using this method it is possible to calculate the longest relaxation time of M for a single domain ferromagnetic particle with large uniaxial anisotropy. It is also possible to calculate the longest relaxation time when the particle is in the presence of an external magnetic field applied... 

The relaxation time T (o-, ) for the magnetization of a single domain ferromagnetic particle with uniaxial anisotropy in the presence of an external field from T = Mp and Eq. (3.129) is... 

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