Berlin 2012 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 38: MagneticThin Films I

MA 38.5: Vortrag

Donnerstag, 29. März 2012, 10:30–10:45, H 0112

An amorphous model system for the 2D XY universality class — •Andreas Liebig¹, Panagiotis Korelis², Martina Ahlberg², Manfred Albrecht¹, and Björgvin Hjörvarsson² — ¹Institute of Physics, Chemnitz University of Technology, D-09107 Chemnitz, Germany — ²Department of Physics and Astronomy, Uppsala University, Box 516, SE-751 20 Uppsala, Sweden

We present a study on the magnetic properties of thin (15 Å) amorphous Fe₈₉Zr₁₁/Al₇₈Zr₂₂ layers in low fields (below 7 mT) around the apparent ordering temperature (140 K). Despite the thickness of 15 Å, the ordering transition is in excellent agreement with the finite 2D XY model, with a Kosterlitz-Thouless temperature of 134.6 ± 0.1 K. A comparison to crystalline systems, for which the crossover to three dimensional behavior is observed for far thinner layers, is made.

Significant polarizability above the ordering temperature is observed, resulting from large-scale magnetic correlations. These long-range correlations are a inherent feature of the 2D XY universality class. A simple model allows the quantification of these correlations.