The terms for the amorphous magnetic phases were coined by Michael Coey in 1970s.[2][3][4] The Greek root spero/speri (Greek: διασπειρω, romanized: diaspeiro) means 'to scatter'.[1][4][a]
Asperomagnetism is the equivalent of ferromagnetism for a disordered system with random magnetic moments. It is defined by short range correlations of locked magnetic moments within small noncrystalline regions, with average long range correlations. Speromagnets possess a permanent net magnetic moment.[2]
An example of a asperomagnets is amorphous YFe3 and DyNi3.[2][5]
Speromagnetism is the equivalent of antiferromagnetism for a disordered system with random magnetic moments. It is defined by short range correlations of locked magnetic moments within small noncrystalline regions, without average long range correlations. Speromagnets do not have a net magnetic moment.[2]
An example of a solid presenting speromagnetism is amorphous YFe2 and can be detected using Mössbauer spectroscopy.[2][5]
Sperimagnetism is the equivalent of ferrimagnetism for a disordered system with two or more species of magnetic moments, with at least one species locked in random magnetic moments.[1][6] Sperimagnets possess a permanent net magnetic moment.[6] When all species are the same, this phase is equivalent to asperomagnetism.[6]
