Experimental determination of inter-sublattice exchange constants in amorphous FeGd alloys

High-field-magnetization measurements were assessed for melt-spun amorphous Fe100–xGdx alloys. Samples with X = 22 and 24 clearly revealed ferrimagnetic spin-flip transition around 100–150 kOe at 4.2 K and their magnetizations linearly increased with increasing magnetic field above the transition. This magnetization process with spin flipping is well understood with molecular field approximation assuming a simple two-sublattice ferrimagnet. Inter-sublattice exchange constants JRT were obtained directly and amplitudes were –16.5×10–16 erg for X = 22 and –18.1×10–16 erg for X = 24 samples. These agree with previously reported values estimated by molecular field analysis