Magnetic Investigation of Pure Manganese and of Several of its Alloys

Arrott, Coles, and Goldman have shown that a parasitic ferromagnetism can be induced at low temperatures in antiferromagnetic α manganese by pickling in nitric acid, and that this effect can be subsequently removed by a vacuum anneal. We have confirmed this result. Furthermore, we have eliminated as possible sources for this effect the presence of hydrogen or nitrogen in solid solution and the formation of nitrides or hydrides. However, strains arising upon transforming from the β phase to the α phase can induce this parasitic ferromagnetism. These results fit well with Li's hypothesis of antiferromagnetic domain boundaries giving rise to parasitic ferromagnetism. According to Li, strains should serve well to stabilize the domain boundaries.