Calculation of magnetization for the ferromagnetically coupled superparamagentic system on the basis of pair approximation

摘要

We have calculated the magnetization for the ferromagnetically coupled superparamagnetic system on the basis of pair approximation. Usually superparamegntic system has no correlation each other as already have been shown in the Cu-Co ferromagnetic cluster system. However the presence of narrow bridges between magnetic cluster seem presumable when magnetic cluster precipitates along with grain boundaries. In this article we have examined such a superparamagnetic system(ferromagnetically coupled superparamagnetism) theoretically. From the series of calculations, magnetization shows the temperature dependence and the influence of thermal fluctuation is found to be larger when the length of bridge becomes longer.