Berlin 2005 – wissenschaftliches Programm
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MA: Magnetismus
MA 5: Spinstrukturen und magnetische Phasenüberg
änge
MA 5.1: Vortrag
Freitag, 4. März 2005, 10:30–10:45, TU EMH225
Oscillatory Curie Temperature in Ultrathin Ferromagnets: Experimental Evidence — •C. Rüdt, A. Scherz, and K. Baberschke — Institut für Experimentalphysik, Freie Universität Berlin, Arnimallee 14, D–14195 Berlin
We determined the Curie temperature TC for 2-3 monolayers of Co/Cu(100) as a function of the Cu-cap thickness dCu by means of the initial ac susceptibility χac(T) in situ in UHV. We found an oscillatory TC(dCu) in agreement with theoretical predictions [1]. The oscillation of TC has been observed for more than two full oscillation periods for the first time in the range of 1 ML ≤ dCu≤6 ML. For that purpose films with a fixed Co thickness and variable Cu cap thickness (evaporated step–by–step) have been prepared. In contrast to theory [1] the oscillation amplitude Δ TC is only a few Kelvin. This can be understood in terms of realistic interlayer exchange parameters [2]. Furthermore, the quantum–well–like oscillatory behavior is superimposed by a monotonic reduction of TC.
Supported by the DFG (Sfb 290, TP A2).
[1] M. Pajda et al., Phys. Rev. Lett. 85, 5424 (2000)
[2] C. Rüdt et al., J. Magn. Magn. Mater. (Letter to the Editor) (2004), in print