We study the magnetic properties of small Mn ring-shaped clusters on a Pt(111) surface in the framework of density functional theory. We find that the Mn atoms possess large magnetic moments, of the order of $4\hspace{0.5em}{\mu }_B$/atom, and have dominating antiferromagnetic interatomic exchange interactions. A quantum confinement effect within the ringlike clusters was found, indicating that even very small clusters can be seen as quantum corrals. The antiferromagnetic exchange couplings lead to collinear magnetic arrangements in simple corrals, as well as complex noncollinear ordering, as vortexlike structures, for the case of corrals with particular geometry where antiferromagnetism becomes frustrated.

• Received 29 August 2010

DOI:https://doi.org/10.1103/PhysRevB.83.014406