Regensburg 2007 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 20: Magnetic Thin Films II

MA 20.11: Vortrag

Mittwoch, 28. März 2007, 17:45–18:00, H5

Non-collinear magnetism of magnetic 3d-monolayers on Cu and Ag (111) surfaces — •Robert Wieser, Elena Vedmedenko, and Roland Wiesendanger — Institut für Angewandte Physik, Jungiusstr. 11, 20355 Hamburg

It has been recently shown that in low-dimensional, 3d transition metal films on noble metal substrates or at the metal-metal interface complex non-collinear spin structures are possible (P. Kurz et al., PRL 86, 1106, (2001)). Understanding of the magnetic ordering in 3d metals on non-magnetic substrates is important as non-collinear structures have been proposed to play a key role for the exchange bias. The magnetic non-collinearity arises due to the delocalized nature of the electrons responsible for magnetic properties of itinerant magnets and super-exchange interactions via the substrate. These phenomena cannot be described in the framework of the simple Heisenberg Hamiltonian. To describe the non-collinear magnetism we generalize the classical Heisenberg spin model by addition of the contributions coming form exchange interaction up to 3rd nearest neighbor, biquadratic exchange and four-spin interactions. In this presentation the results of classical Monte Carlo calculations for monolayers of Mn on Cu(111) and V on Ag(111) will be shown. All interaction parameters come from the first principles calculations. Magnetic ordering of both systems is found to be non-collinear. The low-temperature, stable configuration of Mn/Cu(111) is a 3Q magnetic state. For V/Ag(111) we find a magnetic phase transition between two different stable configurations at T ∼ 20 K. Interestingly both structures are uncompensated.