Berlin 2005 – wissenschaftliches Programm
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MA: Magnetismus
MA 20: Poster:Schichten(1-29),Spintrsp(30-45),Ex-Bias(46-63),Spindyn(64-75),Mikromat.(76-80),Cluster(81-94),Abbv.(95-99),Obflm(100-02),SpElek.(103-09),E-Theo(110-14),Mikromag.(115-16),Spin+PÜ(117-26),Mag.Mat.(127-51),Meth.(152-55),Mol.Mag(156-59),Kondo(160-65
MA 20.120: Poster
Montag, 7. März 2005, 14:00–18:00, Poster TU C
Size-effects on the magnetic phase transition of Fe/GaAs(001) — •Roland Meier, Frank Bensch, Wolfgang Kipferl, and Guenther Bayreuther — Universitätsstraße 31, 93040 Regensburg
For ultrathin single crystalline Fe-films on GaAs(001) an extraordinary sharp magnetic phase transition at Tc was found in addition to a strong uniaxial anisotropy [1]. Furthermore, an effective T3/2-dependency of the spontaneous magnetization is valid at T<1/2· Tc for both, the extended layer and submicron disks [2]. In the present work we study the details of the phase transition in these confined magnetic systems. Approaching Tc, the correlation length of order parameter diverges: in a real Fe/GaAs-system it can exceed one micron. Thus, the critical behavior of submicron-particles should be affected massively by finite size effects. By means of the longitudinal Kerr effect large area ensembles of uniform nanostructures produced with EBL were investigated. We systematically varied structure size (below 100 nm to 1 micron), shape and the distance between the elements. The influence on the phase transition and the Curie temperature is discussed. The determined critical exponents are compared to theoretical models. Ref. [1] F. Bensch, JAP 89, 7133 (2001) [2] W. Kipferl, JAP 95, 7417 (2004)