Distribution of antiferromagnetic domains in Fe-doped NiO thin films on Ru(0001)

Abstract

Antiferromagnetic (AFM) oxide materials in low-dimensional geometries, either in nonmag- netic or magnetic environments, display a rich variety of magnetic behaviors. They are very interesting materials to investigate the fundamental physics of finite-sized effects expressed by magnetic systems. Despite the limited applications in actual technology, AFM oxides represent very important reference and model systems for studying the interface coupling phenomena that are ultimately exploited in devices such as spin-valves. Here we demonstrate a route for preparing high quality ultrathin ternary transition metal oxide films on a metallic substrate. Nickel oxides with a small content of iron have been grown on Ru(0001) by oxygen-assisted molecular beam epitaxy at elevated temperatures (1150 K). The nucleation and growth process are observed in real time by means of Low Energy Electron Microscopy (LEEM), which enables the optimization of the growth parameters. A comprehen- sive characterization is performed combining LEEM and LEED for structural characterization and PEEM (PhotoEmission Electron Microscopy) with synchrotron radiation for chemical and magnetic analysis via X-ray Absorption Spectroscopy and X-ray Magnetic Linear Dichroism (XAS-PEEM and XMLD-PEEM, respectively). We have been able to obtain high quality 2D islands with atomically flat surfaces and low density of defects. The high crystalline and morphological quality result in optimized properties with respect to films grown by other methods, such as magnetic domains which are larger by several orders of magnitude.