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 20.102: Poster
Montag, 7. März 2005, 14:00–18:00, Poster TU C
Reduced Magnetic Ordering Temperatures in Polycrystalline Ho Films — •E. Schierle, E. Weschke, and G. Kaindl — Institut für Experimentalphysik, Freie Universität Berlin, Arnimallee 14, D-14195 Berlin, Germany
The magnetic structure and ordering temperatures of polycrystalline Ho metal films
were studied by magnetic x-ray scattering at the Ho-M5 resonance. Ho metal is
characterized by a long-period helical magnetic structure with a period of 10 layers at 40 K. As recently demonstrated, the helical helical magnetic ordering
temperature drops substantially in single-crystalline films with thicknesses
comparable to the length of the magnetic period [1]. In the polycrystalline films, we observe a substantial reduction of the ordering temperature
even in films as thick as 100 layers, where finite-size effects are expected to be absent. This shows that the magnetic coherence does not extend across the whole film, i.e. exchange coupling across the grain boundaries is negligible and the
helical domains are limited to the individual grains. The work was supported by the BMBF, project 05 KS1KEE/8.
[1] E. Weschke et al., Phys. Rev. Lett. 93, 157204 (2004).