Intrinsic low field susceptibility in pseudobinary DyxY1-> x> Al2andTbxGd1- xAl2 cubic intermetallic compounds
Low field ( Hac ≈ 3.5 x 10 -6T) and low frequency (15 Hz) ac susceptibilities, χ i, have been measured between 3.3 K and well above the Curie temperatures, for the intermetallic Laves phase compounds Dy xY 1- xAl 2 and Tb xGd 1- xAl 2. It is concluded that χ i is, at low enough temperatures, dominated by the domain wall excursions around the minima of the anisotropy Peierls potential wells. The derived model relation χi( T) Hc( i) ( T) = const., where H c(i) is the intrin sic pinning coercive field, is confirmed at low enough temperatures. The shape of the observed susceptibility cusps around the Curie temperatures in the series Dy xY 1- xAl 2 ( x 0.35) suggests that these systems are magnetically inhomogenous. The magnetic domain sizes estimated from these measurements seem quite small (between around 0.01 and 0.1 μm).