ROLE OF OXYGEN IN OBTAINING COMPLETE MAGNETIC FIRST-ORDER TRANSITIONS IN FERH FILMS

In contrast to the sharp first-order transition between antiferromagnetism and ferromagnetism observed in bulk FeRh samples, thin films of the compound were previously reported to have a broad, incomplete, and hysteretic transition. It has now been discovered that when FeRh films are given a diffusion anneal in a good vacuum, and then a second anneal in a N2 atmosphere with a trace of O2 present, a complete transition develops. The improvement in the transition due to the O2 annealing can be removed by annealing in H2. Microstructural differences are also observed in the O 2-annealed samples which have a complete transition. Under some annealing conditions, however, impurities can completely remove the transition characteristic from films. © 1969 The American Institute of Physics.