INTERACTION EFFECTS ON THE TIME-DEPENDENCE OF THE MAGNETIZATION IN RECORDING PARTICLES

The influence of the magnetostatic interactions on the time dependence of the magnetization of assemblies of particles, which are used in ma gnetic recording, with various packing fraction is analyzed. The time effects are studied with measurements of magnetization decay and deduc tion of magnetic viscosity S, fluctuation field H-f, and activation vo lume V-ac. The magnetostatic interactions among the particles are eval uated with measurement of the Delta M deviations from the Wohlfarth eq uation and calculation of the ''Delta plot area,'' which expresses the overall effect of the interactions. The experimental results show a g eneral weakening of time effects with the increase of packing and inte ractions. The magnetization decay, S and H-f decrease, and V-ac increa ses, when p or Delta plot area increase. The strengthening of the inte ractions supports the thermal stability of the particle magnetization. The result is discussed in relation to the evolution of the magnetiza tion reversal induced by the presence of interactions, which make the occurrence of a coherent switching mode more probable. (C) 1997 Americ an Institute of Physics.