Berlin 2012 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 35: Magnetic Heusler Compounds I

MA 35.1: Topical Talk

Mittwoch, 28. März 2012, 15:00–15:30, H 0112

Heusler compounds: theory and experiments on their electronic structure. — •G. H. Fecher — Max Planck Institute for Chemical Physics of Solids, Dresden

It is well known that Heusler compounds are famous for the occurrence of half-metallic ferromagnetism. Recently they were also suggested to belong to the group of topological insulators. It will be shown that there are some more interesting features in the electronic structure of Heusler compounds between metals and insulators and how they can be designed to exhibit spin gapless semiconductivity and spin gapless antiferromagnetism. Spin gapless semiconductors and halfmetallic antiferromagnets are classes of materials that bridge the gap between the properties of metals and semiconductors. Both exhibit peculiar halfmetallic transport properties and are closely related to halfmetallic ferromagnets. In halfmetallic materials, transport is mediated by electrons having only one kind of spin, i.e., the minority or the majority spin. Spin gapless semiconductors exhibit an additional phenomenon, namely, an open bandgap in one spin channel and a closed bandgap (zero bandgap) in the other. Further, halfmetallic antiferromagnets, also referred to as halfmetallic completely compensated ferrimagnets, exhibit spin order without any macroscopic magnetization. They become spin gapless antiferromagnets when the conducting spin channel exhibits a zero bandgap. The evidence for these phenomena will be exemplified by comparing ab-initio calculations to measurements of the electronic structure by photoemission and electronic transport properties.