Magnetic moment, ferromagnetic relaxation

This relaxation time—which, to be specific, we have written in the Landau-Lifshitz representation—has the anticipated behavior the smaller the precession damping constant (the higher the quality factor of the oscillations), the slower does the particle magnetic moment approach its equilibrium position. For ferromagnet or ferrite nanoparticles the typical values of the material parameters are Is Is < 103G, Vm 10 18cm3, and a 0.1. Substituting them in formula (4.28) aty 2 x 108 rad/Oe s and room temperature, one obtains xD 10-9 s. 

Note that Eqs. (4.127)-(4.130) describe only the longitudinal (with respect to the easy axis) relaxation of the magnetic moment. We remark that under condition 0) L, that is, far from the ferromagnetic resonance range, the transversal components of hi = p(e) are of minor importance. 

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