[en] Ion irradiation induced modifications of the thermomagnetic properties of equiatomic FeRh thin films have been investigated. The application of 20 keV Ne"+ ions at different fluencies leads to broadening of the antiferromagnetic to ferromagnetic phase transition as well as a shift of the transition temperature towards lower temperatures with increasing ion fluence. Moreover, the ferromagnetic background at low temperatures generated by the ion irradiation leads to pronounced saturation magnetisation at 5 K. Complete erasure of the transition, i.e. ferromagnetic ordering through the whole temperature regime was achieved at a Ne"+ fluence of 3 × 10"1"4 ions/cm"2. It does not coincide with the complete randomization of the chemical ordering of the crystal lattice

[en] The spatial coherence of hard X-rays provided by a bending magnet of the storage ring BESSY II was investigated by performing Young's interference experiment. The interference pattern was created by the diffraction of two 2 μm pinholes drilled into a thin tantalum foil by focused ion sputtering. Using an energy-dispersive detector with an energy resolution of 200 eV the interference patterns were detected simultaneously between 5 keV< E<16 keV scanning a 5 μm pinhole through the detector window. The set-up is suitable to characterize the coherence properties of the beamline in a simple manner, i.e. to deduce parameters as the effective source size, the coherence length and the visibility. For the present case the visibility was close to 100% at 5 keV and decreased to 20% at 16 keV

[en] We report the structural properties of thin magnetic Permalloy films treated by two different methods: broad beam Ga⁺ ion implantation at an energy of 30 keV as well as annealing at different temperatures under ultrahigh vacuum. Transmission electron microscopy imaging and X-ray diffraction measurements have demonstrated that both ion implantation and annealing (above 300 °C) lead to further material crystallization and crystallite growth. Whereas annealing (above 400 °C) leads to a strain-free state with an almost constant lattice parameter and to a further enhancement of the initial (111) texture, ion beam implantation boosts the growth of small, arbitrarily oriented crystallites and leads to an linear increase in the lattice parameter, introducing microstrain into the sample. The observed decrease in the saturation magnetization for the implanted samples is mainly attributed to the presence of the non-magnetic Ga atoms incorporated in the Permalloy film itself. The increase in the saturation magnetization for the samples annealed at temperatures above 500 °C is explained by an arising dewetting effect since no ordered Ni₃Fe phase was detected with anomalous X-ray diffraction

[en] ⁵⁷Fe doped titanium oxide monocrystals, prepared by ion implantation at different temperatures and subsequent thermal treatment, were characterized by conversion electron Moessbauer spectrometry, synchrotron radiation x-ray diffraction and superconducting quantum interference device magnetometry. After implantation at room temperature Fe is present in divalent state. Upon annealing in high vacuum Fe²⁺ is reduced to metallic Fe for the most part. After implantation at 623 K most iron is in metallic state. During annealing on air Fe is gradually oxidized from Fe²⁺ to Fe³⁺. Depending on preparation conditions and thermal treatment the role of different nanosized secondary phases is discussed in terms of their influence on the magnetic properties of Fe:TiO₂. α-Fe nanoparticles are found to be responsible for ferromagnetism observed in TiO₂.

No abstract available

[en] Installed in 1999 the energy-dispersive reflectometer at the 13.2 bending magnet employs the exponentially decaying white X-ray emission spectrum of the 1.7 GeV storage ring of BESSY II outside the vacuum. Using an energy-dispersive detector specular and longitudinal-diffuse reflectivity spectra of thin films can be recorded simultaneously between 0.2 A^-1< q_z<1.2 A^-1 within a few seconds. The capability of the experiment is demonstrated probing the correlation length of Cd-arachidate and -stearate films at room temperature and its change during annealing. At T=70 deg. C we observe an instantaneous decay of specular Bragg peaks accompanied with an increase of the diffuse scattering. This indicates the onset of the melting of 2D-ordered acid domains. The vertical diffusion coefficient is estimated to be about 2x10^-24 m²/s

[en] We investigated ZnO(0001) single crystals annealed in high vacuum with respect to their magnetic properties and cluster formation tendency after implant-doping with Fe. While metallic Fe cluster formation is suppressed, no evidence for the relevance of the Fe magnetic moment to the observed ferromagnetism was found. The latter along with the cluster suppression is discussed with respect to defects in the ZnO host matrix, since the crystalline quality of the substrates was lowered due to the preparation as observed by x-ray diffraction

No abstract available

[en] It will be reported about the effect of the sputtering gases, Ar and Xe, on FePt clusters formation by magnetron sputtering deposition at high working pressures. All layers, with bulk equivalent thicknesses between 3 to 5 nm, were realized at RT by a sequential layer by layer deposition or a co-deposition of Fe and Pt. After rapid thermal annealing at 500 deg. C, the highest L1₀ fraction was found using Xe as sputtering gas: Xe decreases the transformation activation energy and therefore, reduces the critical thickness necessary to obtain the high anistropic ferromagnetic phase. Ar assisted growths lead to FePt clusters in the L1₀ phase only if the sequential layer deposition is used, whereas for Xe no differences in the deposition techniques were observed

[en] We report on the formation of ion beam induced ripples in Si(001) wafers when bombarded with Ar+ ions at an energy of 60 keV. A set of samples varying incidence and azimuthal angles of the ion beam with respect to the crystalline surface orientation was studied by two complementary near surface sensitive techniques, namely atomic force microscopy and depth-resolved X-ray grazing incidence diffraction (GID). Additionally, cross-section TEM investigations were carried out. The ripple-like structures are formed at the sample surface as well as at the buried amorphous-crystalline interface. Best quality of the ripple pattern was found when the irradiating ion beam was aligned parallel to the (111) planes. The quality decreases rapidly if the direction of the ion beam deviates from (111). (Abstract Copyright [2009], Wiley Periodicals, Inc.)