The magnetic state and magnetic coupling of individual atoms in nanoscale structures relies on a delicate balance between different interactions with the atomic-scale surroundings. Using scanning tunneling microscopy, we resolve the self-assembled formation of highly ordered bilayer structures of Fe atoms and organic linker molecules (T4PT) when deposited on a Au(111) surface. The Fe atoms are encaged in a three-dimensional coordination motif by three T4PT molecules in the surface plane and an additional T4PT unit on top. Within this crystal field, the Fe atoms retain a magnetic ground state with easy-axis anisotropy, as evidenced by x-ray absorption spectroscopy and x-ray magnetic circular dichroism. The magnetization curves reveal the existence of ferromagnetic coupling between the Fe centers.

We present a detailed study on epitaxial bilayers made up of ferromagnetic (FM) Ni and antiferromagnetic (AFM) FexMn1−x layers on Cu(001). The AFM ordering temperature (TAFM) and the coupling at the interface of FM and AFM layer are deduced from polar magneto-optical Kerr effect measurements at different temperatures. The enhancement of coercivity for samples with different FexMn1−x layer thickness, Fe concentration, and FM-AFM interface roughness reveals that TAFM only depends on the layer thickness. The FM-AFM coupling strength is determined by the Fe concentration of the FexMn1−x layer and the interface roughness, but as the first two measurement series clearly show, these do not affect the ordering temperature, unlike earlier results for in-plane magnetization. We explain this difference by assuming that the spin structure of the AFM is distorted from the 3Q structure of the bulk material, in a way that depends on the magnetization direction of the adjacent FM layer. Additionally we discuss the dependence of FM-AFM coupling strength and AFM magnetic anisotropy on Fe concentration and interface roughness concluded from the thickness dependence of exchange-biased hysteresis loops.

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The conditions required for hepatocyte cultures is a main topic in the development of bioreactors for hybrid liver support systems. The detoxification of ammonia and the synthesis of urea due to primary isolated hepatocytes was measured in order to compare two different models of gas supply in bioreactors: (a) indirect medium oxygenation and (b) direct membrane-contact oxygenation of the hepatocytes using polypropylene membranes. Increasing oxygen pressure promoted cell function. At day 6 of culture, urea synthesis was 0.8 5 0.3 mM in 21% of 0, cultures and 1.5 f 0.1 mM in oxygenated cultures. Alkalosis due to CO, loss decreased ammonia metabolism. The direct membrane-contact oxy-

Single-ion lanthanide-organic complexes can provide stable magnetic moments with well-defined orientation for spintronic applications on the atomic level. Here, we show by a combined experimental approach of scanning tunneling microscopy and X-ray absorption spectroscopy that dysprosium--tris(1,1,1-trifluoro-4-(2-thienyl)-2,4butanedionate) (Dy(tta)3) complexes deposited on a Au(111) surface undergo a molecular distortion, resulting in distinct crystal field symmetry imposed on the Dy ion. This leads to an easy-axis magnetization direction in the ligand plane. Furthermore, we show that tunneling electrons hardly couple to the spin excitations, which we ascribe to the shielded nature of the 4f electrons.