Berlin 2008 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 8: Magnetic Imaging
MA 8.4: Vortrag
Montag, 25. Februar 2008, 16:00–16:15, H 1012
Slow magnetic dynamics observed by photon correlation spectroscopy — Stan Konings1, •Christian Schüßler-Langeheine2, Holger Ott2, Eugen Weschke3, Enrico Schierle3, and Jeroen B. Goedkoop1 — 1Van der Waals Zeeman Institute, University of Amsterdam — 2II. Physikalisches Intitut, Universität zu Köln — 3Institut für Experimentalphysik, Freie Universität Berlin
Slow dynamics on nm length scales and time scales longer than 1 µs is best observed by x-ray photon-correlation spectroscopy (XPCS). The method uses the static interference pattern caused by the scattering of coherent x-rays from a sample containing disorder (speckle). When the system fluctuates the speckle pattern changes on the time scale of the fluctuations in the sample itself. From the dynamics of the speckle pattern the dynamics in the sample can hence be determined. We present the first application of this approach to slow magnetic domain fluctuations in an antiferromagnetic system using PCS in soft x-ray resonant magnetic diffraction. Ultrathin Ho metal films show a decay of long-range magnetic order over an unusually broad temperature range. Using PCS we can identify domain wall pinning as the dominant mechanism causing this broadened phase transition [1].
[1] S. Konings et al., cond-mat/0707.2765