Regensburg 2007 – scientific programme

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MA: Fachverband Magnetismus

MA 28: Surface Magnetism

MA 28.9: Talk

Thursday, March 29, 2007, 17:15–17:30, H23

Non-collinear magnetic order in one monolayer Fe on Ru(0001) — •Björn Hardrat¹, Paolo Ferriani¹, Marjana Ležaić², and Stefan Heinze¹ — ¹Institute of Applied Physics and Microstructure Research Centere, University of Hamburg, 20355 Hamburg, Germany — ²Institut für Festkörperforschung, Forschungszentrum Jülich, 52425 Jülich, Germany

Two-dimensional (2D) antiferromagnetic systems on hexagonal lattices are expected to exhibit non-collinear order due to the inherent topological frustration of exchange interaction. We propose one ML Fe on Ru(0001) as a good candidate for the observation of a non-collinear magnetic structure in a 2D system. Experimentally, no long range ferromagnetic order was observed down to a temperature of 100K [1]. Surprisingly, density functional theory (DFT) calculations based on the local density approximation found a row-wise antiferromagnetic ground state [2]. We have performed calculations of the Fe ML on Ru(0001) in the generalized gradient approximation of the DFT, using the full-potential linearized augmented plane wave method, as implemented in the FLEUR code (www.flapw.de). We have explicitly taken non-collinear states such as spin-spirals into account. Among all solutions of the Heisenberg model, we obtain the Néel state with an angle of 120^∘ between magnetic moments of adjacent atoms as the magnetic ground state. We have further determined the Heisenberg exchange constants and considered the effect of higer order spin interactions such as the biquadratic and four-spin interaction.

[1] Liu et al. PRB 41 553 (1990) [2] Wu et al. PRB 44 4449 (1991)