Atomically flat Fe-doped cobalt ferrite single crystal islands with μm-sized magnetic domains

Poster presented at the 31st European Conference on Surface Science (eccos 31), held in Barcelona (Spain) on August 31st - September 4th, 2015. Oxide surfaces and thin/ultra-thin oxide films (P-Mo-069 to P-Mo-095).CoFe2O4 (CFO) is an oxide of the spinel family. Stoichiometric CFO is electrically insulating and ferrimagnetic, with a high anisotropy and a large magnetostriction [1]. Changing its structure, for example by substitution of the different cation sites, offers the possibility of manipulating its physical properties. In particular, upon Fe doping, its electrical resistivity decreases linearly while its magnetic moment increases in a non-linear fashion [2,3]. The capacity of tuning the physical properties of CFO by doping makes it a promising material for spintronic devices. We here present Fe-doped CFO single crystal islands grown on Ru(0001) by reactive molecular beam epitaxy (MBE). In situ low-energy electron microscopy (LEEM) permits tailoring the epitaxial growth in order to obtain micron-sized defect-free crystals of nm thickness. The magnetic domains distribution and the magnetic moments were studied by X-ray absorption (XAS) and X-ray Magnetic Circular Dichroism (XMCD) at the CIRCE beamline at the ALBA Synchrotron. Contributions to the XMCD spectra of the different cationic species were determined by simulations using the CTM4XAS 5.5 program. The stability of the films in air permits ex situ studies such as AFM and MFM in order to obtain valuable complementary information