Fe nanodots formed on a metalorganic network: growth and magnetism

Abstract

Nanostructured Fe clusters whose atoms have a low average coordination number are expected to present enhanced orbital magnetic moment and anisotropy. Metal-organic interactions exhibit custom reversibility in bond formation that may result in large and extended self-assembled structures. Under ultra-high vacuum conditions, we use a Cu(111) monocrystal as substrate and generate an extended metalorganic network that fully covers its surface, which is stable at room temperature. When Fe is evaporated onto this molecular array, instead of the usual triangular bi-layer islands, single atomic height nanoclusters are formed (Fig. 1). The obtained structures are characterized as a function of coverage and temperature by means of Scanning Tunneling Microscopy. We find that both parameters affect the resulting nanodot sizes implying that a certain control can be exerted on its fabrication. Moreover, X-ray Magnetic Circular Dichroism experiments onto these samples show that the Fe nanostructures, which are stable at room temperature, significantly change the magnetic anisotropy compared to the case when the molecular layer is missing.