Microstructure studies of ultra-thin BaTiO3 thin films (2-10 nm thick) show nano-domains having a width as small as one unit cell. Only 180° nano-domains are formed in multi-domains structures. The domain-boundaries are formed at {001} twin boundaries. Most of the domains are oriented in parallel to the film plane but out-of-plane orientations are also observed. The films exhibit ferroelectric behavior characterized by a polarization hysteresis loop and a relatively fast switching time. A remnant polarization of about 0.5 μC/cm2 and coercive field of 2.7 V/cm were measured in parallel to the film plane. Temperature-dependent measurements show two peaks of the dielectric constant at about 60°C and 115°C. These peaks are attributed to two transition temperatures associated with the orientation of the nano-domains relative to the film plane and stress.

Extended abstract of a paper presented at Microscopy and Microanalysis 2011 in Nashville, Tennessee, USA, August 7–August 11, 2011.

Co/Pt thin film multilayers with strong perpendicular anisotropy and out-of-plane coercivities of 5-11 kOe were magnetically altered in areas of local ion beam interaction. The ion irradiations were performed by ion projection through silicon stencil masks fabricated by silicon on insulator (SOI) membrane technology. The ion projector at the Fraunhofer Institute for Silicon Technology (ISiT) was operated at 73 keV ion energy and with a 8.7- fold demagnification. After exposure to 3 × 1014Ar+/ cm2 magnetic islands smaller than 100 nm in diameter were resolved in the Co/Pt multilayersby means of magnetic force microscopy. The impact of different ion species (He+, Ar+ and Xe+) and ion energies (10 – 200 keV) on the multilayer structure was evaluated using Monte Carlo simulations. The ballistic interface intermixing was used to predict magnetic coercivity changes for various irradiation conditions. The simulations revealed that with 73 keV Ar+ and Xe+ ions the irradiation dose could be reduced by a factor of 100 and 400 respectively in comparison to 73 keV He+which was verified in the experiments. X-ray reflectivity measurements confirmed that the Co/Pt superlattice structure is slightly weakened during the irradiation and that the surface smoothness of the media is preserved. Using the Ion Projection Process Development Tool (PDT) at IMS-Vienna concentric data tracks including head positioning servo informations were patterned onto a 1” IBM microdrive™ glass disk which was coated with Co/Pt multilayers. In a single exposure step several tracks within an exposure field of 17 mm in diameter were structured by 2 × 1015He+/ cm2 at 45 keV using a 4- fold demagnification set-up.

We describe single-target ion beam sputtering of superconducting YBaCuO thin films mainly onto R-sapphire and (100) SrTiO3 substrates. We discuss different thermal treatments and consequent X-ray and resistivity results and conclude with X-ray photoelectron spectroscopy data which indicate formation of hydroxydes on the surface of films exposed to atmosphere.

Using mesotaxy, a technique which involves high dose implantation followed by high temperature annealing, we have created narrow wires of CoSi2 buried beneath the surface of a silicon wafer. The implantation masks are fabricated directly on the silicon substrate using high resolution electron beam lithography in combination with reactive ion etching. TEM analysis shows that the wires are single-crystal and oriented with the substrate with very abrupt interfaces. The electrical continuity of the wires has been confirmed with electron-beam-induced current measurements.

The surface spin-flop and Néel transitions are examined in Fe/Cr superlattices. The surface spin-flop, originally predicted by Mills [Phys. Rev. Lett. 20, 18 (1968)], is observed in Fe/Cr(211) superlattices with antiferromagnetic interlayer coupling and uniaxial in-plane anisotropy. The Néel transition (TN) of Cr is observed in Fe/Cr(001) superlattices, for which the onset of antiferromagnetism is at a thickness tCr of 42Å. The bulk value of TN is approached asymptotically as tCr increases and is characterized by a three-dimensional shift exponent. These TN results are attributed to finite-size effects and spin-frustration near rough Fe-Cr interfaces.

In 2005 we obtained very precise interferometric measurements of the pole-on rapid rotator Vega (A0 V) with the longest baselines of the Center for High Angular Angular Resolution (CHARA) Array and the Fiber Linked Unit for Optical Recombination (FLUOR). For the analysis of these data, we developed a code for mapping sophisticated PHOENIX model atmospheres on to the surface of rotationally distorted stars described by a Roche-von Zeipel formalism. Given a set of input parameters for a star or binary pair, this code predicts the interferometric visibility, spectral energy distribution and high-resolution line spectrum expected for the system. For the gravity-darkened Vega, our model provides a very good match to the K-band interferometric data, a good match to the spectral energy distribution – except below 160 nm – and a rather poor match to weak lines in the high dispersion spectrum where the model appears overly gravity darkened. In 2006, we used the CHARA Array and FLUOR to obtain high precision measurements of the massive, non-eclipsing, double-line spectroscopic binary Spica, a 4-day period system where both components are gravity darkened rapid rotators. These data supplement recent data obtained with the Sydney University Stellar Interferometer (SUSI). Our study follows the classic 1971 study by Herbison-Evans et al. who resolved Spica as a binary with the Narrabri Stellar Intensity Interferometer (NSII). We will report on our progress modeling the new interferometric and archival spectroscopic data, with the goal towards better constraining the apsidal constant.

The substitution sites of Pb and Dy dopants in the cuprate-type high temperature superconductor Bi2Sr2Ca1Cu2O $_{8+\delta}$ are determined by a direct comparison of the angle-scanned X-ray photoelectron diffraction (XPD) patterns. We demonstrate the power of XPD as a fingerprinting tool and conclude that Pb occupies Bi sites and Dy the Ca sites. The presence of the incommensurate lattice modulation is not visible in XPD, probably due to a Pb-induced, reduced modulation amplitude.

The SEM, XRD, FFIR and DTA analyses of different size-fractions of clay material from sandstone reservoirs which have experienced a large range of burial conditions have been used to examine the different steps of the depth-related kaolinite-dickite reaction. Dickite progressively replaced kaolinite within a range of burial depths estimated between about 2500 m and 5000 m. The kaolinite-to-dickite reaction proceeds by gradual structural changes concomitant to crystal coarsening and change from booklet to blocky morphology. The crystallization of dickite proceeds by two distinct paths: (1) Accretion of new material from either dissolution of smaller unstable kaolinite crystals and/or detrital minerals (chiefly feldspars), on early-formed coarser metastable kaolinite crystals which exert extended morphological control on the growing crystals. (2) Neoformation of ordered dickite which will continue to grow by a dissolution-crystallization process. The kaolinite-todickite reaction is kinetically controlled and anomalies in the kaolinite/dickite ratio observed in certain sandstone reservoirs may be used to assess the timing of invasion by hydrocarbons.

The common treatment modalities for depression, i.e. pharmacotherapy and psychotherapy have the significant disadvantage of at least a three- to four-week time lag between initiation of treatment and amelioration of mood. Total sleep deprivation (TSD) in contrast, leads to an immediate antidepressant effect in 60% of the patients. However, it has gained only little clinical relevance as usually the improvement is only transient and almost regularly reversed by the next nights of sleep. A procedure preserving the antidepressive effect of sleep deprivation would therefore be of high clinical relevance.

Radiocarbon analyses by accelerator mass spectrometric (AMS) techniques on organic fractions of human bone from various North American localities previously assigned ages ranging from about 70,000 to 15,000 years B.P. now suggest that none of these skeletons is older than 11,000 C-14 years B.P.