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MA: Magnetismus

MA 32: Magnetic Particles / Clusters

MA 32.5: Vortrag

Donnerstag, 30. März 2006, 16:15–16:30, HSZ 401

Magnetic moments of mass-selected FeCo alloy clusters on Ni(111)/W(110) — •R.K. Gebhardt¹, A. Kleibert², J. Bansmann^2,3, F. Bulut¹, K.-H. Meiwes-Broer², and M. Getzlaff¹ — ¹Institute of Applied Physics, University of Düsseldorf, Germany — ²Institute of Physics, University of Rostock, Germany — ³Institute of Surface Chemistry, University of Ulm, Germany

FeCo-alloys yield the highest magnetic moments of all binary 3d-transition metal alloys, such as Fe₅₀Co₅₀ about 2,5 µB (Slater-Pauling-curve). We prepared Fe₅₆Co₄₄ clusters (5 - 6 nm diameter) using the arc cluster ion source (ACIS) working in a continuous mode. The clusters were mass-selected by an electrostatic quadrupole deflector and subsequently deposited on Ni(111)/W(110). We present X-ray absorption measurements recorded under different angles. The investigation of the X-ray magnetic circular dichroism (XMCD) allows us to determine element-specifically the magnetic spin- and orbital moments. Measurements of the magnetic moments of larger clusters (7,5 nm diameter) are in a good agreement with the theoretically expected values in the solid [1,2]. Furthermore, the absorption measurements permit an estimation of the stoichiometry. Comparison of the angle-dependent absorption spectra gives indication of the cluster shape. The relation between size and magnetic properties will be discussed.

[1] J. Bansmann and A. Kleibert, Appl. Phys. A 80 (2005) 957

[2] M. Getzlaff et al., Appl. Phys. A 82 (2006) 95