In this Paper the superparamagnetism of the oxidzed surface layer of fine iron paricles is reported. Fine iron particles in the range of size from 15 to 50nm with oxidized surface ayer were prepared by evaporation in nitrogen atmosphere. The sizes were measured by the BET method and transmission electron microscope (TEM). X-ray and electron diffraction analysis show that the particle is coposed of α-Fe core and a sufrface layer of Fe3O4. The thickness of the outer oxidized layer is about 2nm and is independent of the average diameter of the particles. The results indicate that the transition of the domain structure plays an important role in the superparamagnetic behavior of the oxide surface layer of iron particles. The emergence of the superparamag-netism at low temperature, may be a diagnostic of the transttion from the smgle domain to multi-domain structre for inner core. The criticle size of the single domain domain is esatimated at-about 40nm.

Using a quantum-optical setting, we demonstrate local-realism violation for a maximally entangled state of two particles without using inequalities. Our proof can be generalized to all arbitrary entangled states for two particles.

Y1.6Ca1.4V0.4sSn0.5Fe4.05O12 has been bombarded with a 0.56 GeV C6+ ion beam. The vacancies and vacancy clusters induced by the irradiation change the directions of hyperfine fields around the defects. The reduction of the magnetic hyperfine field is caused by the lower superexchnage field due to the formation of the O2- vacancies. The change of direction of the hyperfine field has also been observed in Mtissbauer spectra. X-ray diffraction showed that the defects give rise to an increase of the lattice constantof the samples.

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