Berlin 2008 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 8: Magnetic Imaging

MA 8.3: Vortrag

Montag, 25. Februar 2008, 15:45–16:00, H 1012

Real space imaging of 2-dimensional 120^∘ Néel structure: one monolayer Mn on Ag(111) — •Chunlei Gao¹, Wulf Wulfhekel^1,2, and Jürgen Kirschner¹ — ¹Max Planck Institute of Microstructure Physics, Halle, Germany — ²Physikalisches Institut, Universität Karlsruhe (TH), Wolfgang-Gaede Strasse 1, Karlsruhe, Germany

In magnetic materials, the competing exchange interaction between neighboring atoms very often leads to frustrated spin structures. Magnetic frustration may have chemical or topological origin. A classical example of a topological frustration is a 2-dimensional triangular lattice of antiferromagnetic atoms in which a noncollinear 120^∘ Néel structure stabilizes. In this report, we demonstrate the 120^∘ Néel structure of Mn monolayer on Ag(111) with spin-polarized scanning tunneling microscopy (Sp-STM) operating in the constant current mode [1]. Mn grows as monolayer triangular islands either on fcc or hcp atomic sites. The existence of structurally equivalent, but magnetically distinguished Mn islands of the same atomic site is observed. The fcc and hcp islands are found to have the same 120^∘ Néel structure but with different orientation of the moments which means the fcc and hcp islands have different magnetic anisotropy.

[1]D. Wortmann, S. Heinze, Ph. Kurz, G. Bihlmayer, and S. Blügel, Phys. Rev. Lett. 86, 4132 (2001)