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Transmission x-ray microscopy with the x-ray magnetic circular dichroism as a contrast mechanism was used to image the field dependent evolution of magnetic domains in artificially nanostructured strips of a multilayered Fe/Gd system. A diversity of domain configurations have been imaged for different strengths of the applied magnetic field and different widths of the strips, varying between 100 nm and 1 μm. Undulating domain patterns, analogous to those observed in other condensed matter Systems could be found.

Bei der Umsetzung von reduzierten Phillips‐Katalysatoren mit Ethylen bei 300 °C wird der Katalysator nach kurzer Zeit desaktiviert; gleichzeitig entstehen trägergebundene Chrom‐Organyle. Diese können vom Silicagel‐Träger mit HCl und anderen Säuren gespalten und mit CH3OH extrahiert werden. Durch Chromatographie werden Fraktionen von Organochrom‐Verbindungen erhalten, die sich um CH2‐Einheiten unterscheiden. XPS‐, 1/2H‐NMR‐ und Massenspektren sowie magnetische Messungen beweisen, daß Homologe des Typs (RnCp)CrCl2(CH3OH) (RnCp = alkyliertes Cyclopentadienyl) vorliegen. Der RnCp‐Ligand bildet sich durch oxidative Verknüpfung, – ggf. unter CC‐Spaltung – von Chrom‐gebundenem Olefin. Gemäß UV/Vis‐ und Massenspektren können Cl–und CH3OH durch andere Anionen und Donormoleküle ersetzt werden. Ohne Donor werden zweikernige, Cl‐verbrückte Moleküle erhalten, von denen [(1,2,3‐Me3Cp)CrCl2]2durch Kristallstrukturanalyse gesichert wurde. Einwirkung von O2führt reversibel zu Chrom(V)‐Derivaten vom Typ (RnCp)Cr(O)Cl2.

Using an alternating gradient magnetometer (AGM) magnetic after-effects have been observed in ultrathin ferromagnetic films for the first time. The relaxation time of magnetic reversal in epitaxial cobalt films on Au(111) in a constant applied field varies over several orders of magnitude depending on field and film thickness. The extrapolated relaxation time in zero field increases from 14 days to 11 years if the film thickness is reduced from 9.5 to 5.4Å. This should be an adequate stability for most practical applications of such films.

We succeeded in growing ultrathin Fe(110) films in ultrahigh vacuum sandwiched between Au(111), which show ferromagnetic behaviour even below monolayer coverage. For the first time, low-temperature magnetization measurements on such Au-Fe-Au sandwiches reveal a switching of the easy axis from the film plane to the film normal in iron films thinner than 3 monolayers (ML). We interpret this as an interface effect. The usually dominating shape anisotropy is overcompensated by a magnetic interface anisotropy at smaller iron coverages. The effective magnetic anisotropy field at 10 K is proportional to the inverse iron thickness down to 2 ML. The related interface anisotropy field is determined to 40 kOe per single Fe(110)-Au interface.

Abstract: The use of He-filled proportional counters for CEMS studies with57Fe is very attractive because of their high efficiency. Stability problems at low temperature have been solved by using an electronic feed back which controls the anode voltage to keep the gas gain constant. Long term stable operation has been achieved between 370 K and 50 K. The potential of the counter is demonstrated on epitaxial and amorphous magnetic thin films.

Abstract: The magnetic ground state, magnetic anisotropies and spin excitations of surfaces, interfaces and ultra-thin films of ferromagnetic 3d-metals are discussed. Enhanced magnetic ground state moments and altered hyperfine fields as predicted by ab initio band calculations have not been conclusively verified by experiments up to now. Future calculations should take into account dipolar fields and the role of interface roughness. Very large magnetic anisotropies are observed at magnetic surfaces and interfaces. In Ni/Cu multilayered films, the superposition of surface and stress-induced anisotropies was used to switch the easy axis of magnetization from the film plane to a perpendicular orientation by a proper choice of the Ni layer thickness. This could be an attractive possibility to develop new magnetic materials for technical applications. The temperature dependence of the spontaneous magnetization at surfaces and in ultra-thin films deviates from the behaviour of bulk material. Size effects as well as surface effects of spin wave excitations are discussed, comparing theoretical and experimental results. The need for more complete theories including surface exchange, surface anisotropy and realistic surface structures is emphasized.

The overall fall-back angle a50 of thin uniaxial ferromagnetic films was calculated including the effect of the magnetization ripple and the skew. Both, ripple and skew angle were assumed to show a Gaussian distribution with different standard deviations. Ripple and skew are superimposed in a nonlinear manner to give the fall-back angle of the entire film. By direct measurements of the ripple fall-back angle, a500, for very small spots of the film, of the fall-back angle, a50, of the entire film, and of the distribution and standard deviation of the skew, the calculation could be tested, which gave good agreement between experiment and theory. As long as the skew is unknown the fall-back angle alone is not the best measure for the “quality” of an uniaxial film.

Combining X‐ray magnetic circular dichroism (X‐MCD) with a transmission X‐ray microscope (TXM) allows to image element‐specifically magnetic domain structures with 25 nm lateral resolution. Both in‐plane and out‐of‐plane systems can be studied in applied magnetic fields. Thus field‐dependent parameters, as individual nucleation fields in magnetic nanostructures can be deduced and related to morphology. Images of thermomagnetically written bits in magneto‐optical TbFeCo media proof the reliability of the writing process and the importance of an exact thermal design of the systems. Domains observed at corresponding Co L edges proof the chemical sensitivity of M‐TXM and its potential to image few monolayer systems.

The magnetization, M(H, T), of sputtered Fe1−xBxamorphous films was measured using a SQUID magnetometer in the temperature range 2 K ⩽ T⩽ 400 K in fields up to 50 kG. Ground state magnetic moments, hyperfine fields and spin wave parameters Band Care discussed as a function of boron concentration (0.16 ⩽ x⩽ 0.49), which was determined by an elaborate procedure using AES.