Berlin 2012 – scientific programme

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O: Fachverband Oberflächenphysik

O 50: [MA] Joint Session "Surface Magnetism I" (jointly with O)

O 50.9: Talk

Wednesday, March 28, 2012, 18:15–18:30, BH 243

Exchange interactions in Fe clusters on Rh(111) and Ru(0001) from first principles — •Fabian Otte, Paolo Ferriani, and Stefan Heinze — Institute of Theoretical Physics and Astrophysics, University of Kiel, Leibnizstr. 15, 24098 Kiel, Germany

In the last few years it has been found that a non magnetic substrate can dramatically affect the magnetic properties of an adsorbed magnetic monolayer. For example, the nearest neighbor exchange of a Fe monolayer, which is the prototypical ferromagnetic material, becomes antiferromagnetic on W(001) [1] and Ru(0001) [2], while complex non-collinear magnetic order has been observed on Fe/Ir(111) [3].

Motivated by XMCD experiments [4] that found a surprisingly small dichroism in Fe clusters on Rh(111) and Ru(0001), we studied the magnetic properties of these systems by means of density functional theory calculations, using the projector augmented planewave method as implemented in the VASP-code. We considered collinear magnetic states and cluster sizes up to five atoms with different geometries and mapped total energy calculations onto an effective Heisenberg model. We found a complex trend of the magnetic exchange interaction which alternate between ferro- and antiferromagnetic depending on cluster size, geometry and interatomic distance.

[1] P. Ferriani et al., Phys. Rev. Lett. 94, 087204 (2005). [2] B. Hardrat et al., Phys. Rev. B, 79, 094411 (2009). [3] S. Heinze et al., Nature Physics 7, 524-526 (2011). [4] V. Sessi, S. Krotzky, M. Wasnioska, C. Tieg, J. Honolka and K. Kern, private communication