The complicate interplay between different contributions, such as symmetry, nearest-neighbor distance, and hybridization with the substrate plays a crucial role in determining the magnetic ground state of transition metal films in the monolayer regime. For example, a complex antiferromagnetic structure has been observed in the pseudomorphic Fe monolayer on Ir(111) as a consequence of the strong Fe-Ir hybridization and the strained Fe fcc structure [1].
Here we report on the magnetism of the Co and Fe monolayer on Rh(111). The Rh lattice constant (3.80 Å) is very close to that of Ir (3.84 Å), however the electronic structure is quite different because Rh is a 4d8 while Ir is a 5d7. Therefore, a comparison of the magnetic structure on the surfaces should help to understand and quantify the different contributions. We find a ferromagnetic order of the Fe monolayer with a magnetization easy axis perpendicular to the surface and a spin moment close to 2.4 μB. For the Co monolayer we find an in plane magnetization easy axis with a magnetic moment of 2.08 μB.
[1] K. von Bergmann, S. Heinze, M. Bode, E.Y. Vedemedenko, G. Bihlmayer, S. Blügel, and R. Wiesendanger, Phys. Rev. Lett. 96, 167203 (2006)
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