Berlin 2012 – wissenschaftliches Programm
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MM: Fachverband Metall- und Materialphysik
MM 17: Poster Session
MM 17.77: Poster
Montag, 26. März 2012, 17:00–19:00, Poster B
Enhanced Ferromagnetism in Nanometallic Glass studied by Mössbauer spectroscopy — •Ralf Witte1,2, Tao Feng1, Mohammad Ghafari1, Robert Kruk1, Richard Brand1, Herbert Gleiter1, and Horst Hahn1,2 — 1Karlsruher Institut für Technologie, Institut für Nanotechnologie, D-76344 Eggenstein- Leopoldshafen — 2Technische Universität Darmstadt, Gemeinschaftslabor Nanomaterialien, Petersenstr. 23, D-64287 Darmstadt
Interface or grain boundary effects in materials have been widely investigated since the discovery of nanocrystalline materials. In the next step these studies have been extended to another interesting class of materials such as nanoglasses or nanostructured amorphous solids. These materials can be produced by synthesis of amorphous nanoparticles in an inert-gas-condensation (IGC) process and subsequent compaction in UHV. The resulting solid material is characterised by its increased density of structural defects (interfaces) and drastically increased free atomic volume in the interfaces between the glassy nanoparticles. We report on a study using Mössbauer spectroscopy and magnetic property measurements of a nanoglass prepared from amorphous Fe90Sc10 nanoparticles. The material investigated exhibits dramatic changes in magnetic properties, namely an increased magnetic transition temperature by more than 200 K and enhanced magnetic hyperfine fields compared to the structurally homogeneous amorphous material. We attribute this newly identified magnetic phase to the glass-glass interfaces, where the decreased atomic density leads to enhanced exchange interactions following the Bethe-Slater formalism.