A basis of amorphous ferrimagnets

The effects of the fluctuation of exchange interactions on Tc, Tcompand magnetizations in amorphous rare earth-transition metal ferrimagnetic alloys are discussed by the use of effective-field theory with correlations (EFT). It is discussed that the role of the fluctuation of exchange interactions is important for analyzing their experimental data. An amorphous ferrimagnetic insulator with a fractional effective dimensionality is investigated within the same framework. A number of interesting phenomena are obtained for the magnetic quantities of these systems.