Berlin 2005 – scientific programme

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MA: Magnetismus

MA 5: Spinstrukturen und magnetische Phasenüberg
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MA 5.1: Talk

Friday, March 4, 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 T_C for 2-3 monolayers of Co/Cu(100) as a function of the Cu-cap thickness d_Cu by means of the initial ac susceptibility χ_ac(T) in situ in UHV. We found an oscillatory T_C(d_Cu) in agreement with theoretical predictions [1]. The oscillation of T_C has been observed for more than two full oscillation periods for the first time in the range of 1 ML ≤ d_Cu≤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 T_C 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 T_C.

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