Regensburg 2010 – wissenschaftliches Programm

Bereiche | Tage | Auswahl | Suche | Downloads | Hilfe

O: Fachverband Oberflächenphysik

O 28: Surface or interface magnetism

O 28.5: Vortrag

Dienstag, 23. März 2010, 11:30–11:45, H48

Nanoscale Iron with Extraordinary Magnetic Anisotropy — •Thomas Lödding¹, Christian Praetorius¹, Greg A. Ballentine^1,4, Kai Fauth^1,3, Armin Kleibert^2,5, Norman Wilken², Andris Voitkans², and Karl-Heinz Meiwes-Broer² — ¹Physikalisches Institut, Universität Würzburg, Am Hubland, 97074 Würzburg, Germany — ²Institute of Physics, Rostock University, 18051 Rostock, Germany — ³MPI for Metals Research, Heisenbergstr. 3, 70569 Stuttgart, Germany — ⁴Physics Dpt., Brandon University, 270 18th street, Brandon, Canada R7A 6A9 — ⁵Swiss Light Source, Paul Scherrer Institute, 5232 Villigen, Switzerland

We shall show that iron nanocluster ensembles, prepared by deposition of preformed particles onto Cu(111), possess unusual and unexpected features in their magnetic response. We have studied the magnetic moments and response to applied fields using X-ray magnetic circular dichroism as a sensitive element specific probe of the nanocluster magetism. We show that clusters with average diameters of 4 nm and 6 nm not only possess an enhanced magnetization at low temperature but also display an enhanced magnetic anisotropy energy density.

Overmore, a small but non-negligible fraction (≈ 10 %) of the deposited clusters possess extraordinarily large switching fields, i. e. µ₀ H_SW> 0.5 T at T = 12 K for particles with 6 nm diameter. It is evident from our experiments that these large switching fields correspond to intrinsic properties of individual deposited nanoclusters. We shall discuss possible origins of this behavior.