2010 Seminar Series Intermetallic Magnets: From Itinerant Magnetism to Magnetic Refrigeration 2010 Seminar

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  • Intermetallic Magnets: From Itinerant Magnetism to Magnetic

    Refrigeration

    2010 Seminar Series Presents 4:00PM, Monday, December 07, 2009 219 Brown Laboratory

    Professor Gordon Miller iowa stateUniversity, dePartMent of CheMistry

    gmiller@iastate.edu

    Magnetism is governed by the behavior of unpaired electrons in materials that typically contain

    3d transition metals and 4ƒrare-earth metals. For intermetallic compounds containing 3d

    elements, the unpaired electrons are also involved in electronic conduction – so-called itinerant

    magnets. Interatomic exchange coupling can lead to ferromagnetic, antiferromagnetic, or other

    intermediate types of magnetic order, some of which depend on the number of valence electrons.

    When rare-earth metals occur, the 4ƒ electrons are generally localized, and interatomic exchange

    coupling occurs via the conduction band involving the valence 5d orbitals of the rare-earth metals.

    These interactions can be influenced by chemical composition and valence electron count. This seminar

    will summarize some of our recent efforts to study

    the relationships among chemical composition,

    electronic structure and magnetism in three

    different systems:

    (a) transition metal gallides, CrGa-MnGa-FeGa;

    (b) complex metal-rich borides, Sc2Fe(Ru1–

    xRhx)5B2; and (c) rare-earth magnetic refrigerants,

    RE5(SixGe1–x)4. The presentation will identify rules

    for ferromagnetic or antiferromagnetic order

    in 3d itinerant magnets as well as factors

    important for magnetic refrigeration

    applications.

    University of Delaware

    Itinerant Magnetism

    Fe12 Clusters in FeGa

    Giant MCE in Gd5Si2Ge2

    FM vs. AFM in Sc2Fe(Ru1−xRhx)5B2

    Fe Ladders in Ti9Fe2Ru18B8

     

    Department of  