Intrinsic low field susceptibility in pseudobinary DyxY1−> x> Al2andTbxGd1− xAl2 cubic intermetallic compounds

Abstract

Low field ( H ac ≈ 3.5 x 10 -6 T) 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 x Y 1- x Al 2 and Tb x Gd 1- x Al 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 χ i ( T) H c ( 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 x Y 1- x Al 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).