Orientational dynamics of ferrofluids with finite magnetic anisotropy of the particles: relaxation of magneto-birefringence in crossed fields.

摘要: Dynamic birefringence in a ferrofluid subjected to crossed bias (constant) and probing (pulse or ac) fields is considered, assuming that the nanoparticles have finite magnetic anisotropy. This done on basis of general Fokker-Planck equation takes into account both internal external mechanical degrees freedom particle. We describe orientation dynamics terms integral relaxation time macroscopic order parameter. To for an arbitrary relation between (external) anisotropy (internal) fields, interpolation expression proposed justified. A developed description used interpret measurements fluids with high (cobalt ferrite) low (maghemite) The theory appears be full qualitative agreement all experimental data available.