Real and imaginary components of the alternating current magnetic susceptibility of RAl2 (R=Gd, Dy, and Er) in the ferromagnetic region

The real (chi'(ac)) and imaginary (chi " (ac)) components of the ac magneti c susceptibility of the polycrystalline GdAl2, DyAl2, and ErAl2 have been m easured as functions of temperature, ac and bias dc magnetic field amplitud e, and ac magnetic field frequency. Both chi'(ac) and chi " (ac) of the fer romagnetic DyAl2 and ErAl2 are strongly dependent on the ac magnetic field parameters, especially when compared with those of the ferromagnetic GdAl2. The observed behavior of the ac magnetic susceptibility is determined main ly by the domain dynamics, rather than by a change of the exchange interact ions below Curie temperature. (C) 2001 American Institute of Physics.