STUDY OF THE MAGNETIC STATE OF A HIGHLY DISPERSED BAO-CENTER-DOT-6FE(2)O(3) SYSTEM WITH NEAR-CRITICAL PARTICLE-SIZE

An investigation was made of the magnetic state of a system of highly anisotropic BaO . 6Fe(2)O(3) nanocrystals several lattice parameters t hick and having a near-critical volume (similar to 10(-18) cm(3)), Obt ained using cryochemical technology. It is observed that the particles are transformed to the superparamagnetic state and it is shown that t he external magnetic field plays a role in its formation. An H-T diagr am was obtained for the temperature range 300 K-T-c, which shows vario us regions uncharacteristic of the macro-object, which are specificall y attributed to the distribution over the anisotropy fields in the sys tem and the impaired magnetic structure in the surface zone of the par ticles. Relatively large regions of magnetic fields and temperatures w ere observed where reversible rotation of the magnetization vector of particles with near-critical volume plays an important role. (C) 1998 American Institute of Physics.