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

The real (χac′) and imaginary (χac″) components of the ac magnetic susceptibility of the polycrystalline GdAl2, DyAl2, and ErAl2 have been measured as functions of temperature, ac and bias dc magnetic field amplitude, and ac magnetic field frequency. Both χac′ and χac″ of the ferromagnetic 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 mainly by the domain dynamics, rather than by a change of the exchange interactions below Curie temperature.