Regensburg 2013 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 50: Poster II

MA 50.28: Poster

Freitag, 15. März 2013, 10:30–13:30, Poster D

Synthesis and properties of ultrahtin, epitaxial, B2 ordered FeRh thin films — •Ralf Witte^{1, 2}, Richard Brand¹, Robert Kruk¹, and Horst Hahn^{1, 2} — ¹Institute of Nanotechnology, Karlsruhe Institute of Technology — ²Joint Laboratory Nanomaterials, Materials Science Departement, TU Darmstadt

The B2 ordered phase (CsCl structure) of equiatomic FeRh alloys possess interesting magnetic properties. It is antiferromagnetically (AFM) coupled at room temperature and shows a transition to a ferromagnetic phase (FM) at about 400 K. This behavior has been observed in bulk material and as well in thin films. Generally, stabilization of the FM phase is associated with the Rh spin state; in the AFM phase the magnetic moment on the Rh atom is zero, while it gets polarized in the FM state. It has been calculated [1] that the FM state can be stabilized at room temperature in (freestanding, single crystalline) films with a thickness below a critically value of nine atomic layers. This effect is attributed to the increased polarizability of the Rh atoms at the surface, which in turn stabilizes the FM state in the entire film. We present results on the synthesis and properties of such ultra thin, epitaxial FeRh films on MgO substrates prepared by electron beam evaporation. The samples are characterized using e.g. high-resolution X-ray diffraction, atomic force microscopy, SQUID magnetometry, X-ray photo electron spectroscopy and Fe Moessbauer spectroscopy. [1] S. Lounis, Phys. Rev. B 67, 094432 (2003)