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"Magnetism in Minerals: A case study on pyroxenes"

Relatore: Prof. Guenther Redhammer, Universitat Salzburg

Dipartimento di Fisica e Scienze della Terra, Plesso Fisico-Aula Newton)
04 Aprile 2013 ore 15.00

The pyroxenes are import rock forming minerals which are found in a large variety of geological settings with wide chemical compositions. However, they do not only have high significance in geosciences, but also gained vivid interest is solid state physics due a broad variety of magnetic ground states; we find compounds showing pure ferromagnetism, others show antiferromagnetic coupling, some have a dimerized ground state, and some even show multiferroic behaviour. The ground state is determined by the concurring interactions with and between the octahedral chains, hosting the transition metal. In the talk an overview on magnetic ground states in pyroxenes, determined mostly form neutron diffraction experiments, is given: example compounds are - among others - hedenbergite CaFeSi2O6, CaCoSi2O6, aegirine NaFeSi2O6 and LiFeSi2O6, but also the Ge-analogs of these materials and (Fe,Mn,Co)GeO3 pyroxenes.