Berlin 2008 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 13: Surface Magnetism

MA 13.7: Vortrag

Dienstag, 26. Februar 2008, 12:00–12:15, EB 301

Unique playground for non-collinear magnetism : Fe monolayers on hexagonal transition-metal surfaces — •Börn Hardrat, Paolo Ferriani, and Stefan Heinze — Institute of Applied Physics, University of Hamburg, Jungiusstrasse 11, 20355 Hamburg, Germany

Recently, the complexity of magnetic order even in simple systems such as single monolayer (ML) thick magnetic films on non-magnetic substrates has been dramatically demonstrated by the discovery of a spin-spiral state for a Mn ML on W(110) [1] and a nanoscale magnetic structure for an Fe ML on Ir(111) [2].

Here, we use density functional theory calculations based on the full-potential linearized augmented plane wave (FLAPW) method to systematically study the magnetic order of an Fe ML on hexagonal hcp (0001) and fcc (111) surfaces of 4d- and 5d-TMs. We demonstrate that due to substrate d-band filling the exchange coupling changes gradually from antiferromagnetic (AFM) on Tc, Ru, Re, and Os to ferromagnetic (FM) on Rh, Ir, Pd, Os and Pt. On Ru and Re the AFM coupling leads to a non-collinear Néel ground state due to topological frustration of exchange interaction. On Ru, Rh and Ir, the nearest-neighbor exchange coupling is small and exchange beyond nearest-neighbors, higher order spin interactions, and anisotropic exchange interaction compete making these systems a playground for intriguing magnetic order.

[1] M. Bode et al., Nature 447, 190 (2007).

[2] K. von Bergmann et al., PRL 96, 167203 (2006).