8 research outputs found
Superparamagnetic behaviour of antiferromagnetic DyPO4 nanoparticles
We report on the low-temperature magnetic ac-susceptibility of
antiferromagnetic DyPO4 nanoparticles with a very high surface to volume ratio.
The results are interpreted in terms of superparamagnetic relaxation of the
Neel vector arising from a relatively large number approx 0.2 Na of
uncompensated spins probably existing on the surface of the nanoparticles. The
activation energy of the relaxation process is found to be Ea / kB = (2.6+-0.1)
K within a model taking into account the magnetic interaction between
nanoparticles.Comment: 3 pages, 1 figure, Espcrc2, ICM0
Statistics of irreversible displacements of domain walls in nanowires
The process of quasistatic displacement of domain walls is
considered in a nanowire represented as a one-dimensional chain of
ferromagnet crystallites. The domain wall pinning due to spatial
fluctuations of the anisotropy axes is analyzed. Based on the theory
of overshoots of random processes, we have calculated the
distribution functions of the initial susceptibility and of the
maximal force of interaction of the domain wall with inhomogeneities.
These functions are found to be non-Gaussian. We have derived
expressions for the magnetization curve and the coercive force, which
depend on the length of the chain