First-principles characterization of ferromagnetic Mn5Ge3 for spintronic applications

In the active search for potentially promising candidates for spintronic applications, we focus on the intermetallic ferromagnetic Mn5Ge3 compound and perform accurate first-principles FLAPW calculations within density functional theory. Through a careful investigation of the bulk electronic and magnetic structure, our results for the total magnetization, atomic magnetic moments, metallic conducting character and hyperfine fields are found to be in good agreement with experiments, and are elucidated in terms of a hybridization mechanism and exchange interaction. In order to assess the potential of this compound for spin-injection purposes, we calculate Fermi velocities and degree of spin-polarization; our results predict a rather high spin-injection efficiency in the diffusive regime along the hexagonal c-axis. Magneto-optical properties, such as L_2,3 X-ray magnetic circular dichroism, are also reported and await comparison with experimental data.Comment: 10 pages with 6 figures, to appear in Phys. Rev.

Process Reliabilism, Prime Numbers and the Generality Problem

This paper aims to show that Selim Berker’s widely discussed prime number case is merely an instance of the well-known generality problem for process reliabilism and thus arguably not as interesting a case as one might have thought. Initially, Berker’s case is introduced and interpreted. Then the most recent response to the case from the literature is presented. Eventually, it is argued that Berker’s case is nothing but a straightforward consequence of the generality problem, i.e., the problematic aspect of the case for process reliabilism (if any) is already captured by the generality problem

Diode laser modification of ceramic material surface properties for improved wettability and adhesion

To date, very little work has been published with regard specifically to the use of lasers for modifying the surface properties of materials in order to improve their wettability and adhesion characteristics. Using a 60 W high power diode laser (HPDL) the effects of HPDL radiation on the wettability and adhesion characteristics of certain ceramic materials have been determined. It was found that laser treatment of the materials surfaces’ modified the surface energy and accordingly, wetting experiments, by the sessile drop technique using a variety of test liquids, revealed that laser treatment of the range of ceramic materials surfaces resulted in a decrease in the contact angles. The work shows clearly that laser radiation can be used to alter the wetting and adhesion characteristics of a number of ceramic materials by means of changing the surface energy

Consistently Simulating a Wide Range of Atmospheric Scenarios for K2-18b with a Flexible Radiative Transfer Module

The atmospheres of small, potentially rocky exoplanets are expected to cover a diverse range in composition and mass. Studying such objects therefore requires flexible and wide-ranging modeling capabilities. We present in this work the essential development steps that lead to our flexible radiative transfer module, REDFOX, and validate REDFOX for the Solar system planets Earth, Venus and Mars, as well as for steam atmospheres. REDFOX is a k-distribution model using the correlated-k approach with random overlap method for the calculation of opacities used in the $\delta$-two-stream approximation for radiative transfer. Opacity contributions from Rayleigh scattering, UV / visible cross sections and continua can be added selectively. With the improved capabilities of our new model, we calculate various atmospheric scenarios for K2-18b, a super-Earth / sub-Neptune with $\sim$8 M$_\oplus$ orbiting in the temperate zone around an M-star, with recently observed H$_2$O spectral features in the infrared. We model Earth-like, Venus-like, as well as H$_2$-He primary atmospheres of different Solar metallicity and show resulting climates and spectral characteristics, compared to observed data. Our results suggest that K2-18b has an H$_2$-He atmosphere with limited amounts of H$_2$O and CH$_4$. Results do not support the possibility of K2-18b having a water reservoir directly exposed to the atmosphere, which would reduce atmospheric scale heights, hence too the amplitudes of spectral features inconsistent with the observations. We also performed tests for H$_2$-He atmospheres up to 50 times Solar metallicity, all compatible with the observations.Comment: 28 pages, 13 figures, accepted for publication in Ap

A simple squeezer for removal of interstitial water from ocean sediments

A simple and inexpensive squeezer employed in the removal of interstitial water from ocean sediments has been designed. Squeezing is carried out with nitrogen at pressures of 500 to 1000 lb/in2 (35 to 70 kg/cm2). The apparatus is lined with teflon, thus insuring complete freedom from metallic contamination

Ichnofossilien im Campanium des südöstlichen Münsterlandes

In dieser Arbeit werden die Ichnofossilen des Obercampans der südöstlichen Münsterländer Kreidemulde im Raum Beckum/Ennigerloh vorgestellt. Die Kalk-Mergel-Wechselfolgen der Beckum- und Vorhelm-Schichten sind durch kalziklastische, debritische und turbiditische Schüttungen in feinkörnige pelagische Mergel charakterisiert. Im Wesentlichen der Nereites-Ichnofazies zugehörig, fußt die Ausbildung der Ichnofauna hauptsächlich auf sedimentologische Parameter. Ist die Ichnofossilvergesellschaftung der Pelagite durch eine reichhaltige Graptoglyphen-Fauna und Chondrites charakterisiert, die eine ruhige und kontinuierliche Sedimentakkumulation dokumentieren, so bildet sich mit Schüttung der Debrite und Turbidite, und der damit verbundenen Zufuhr von Nährstoffen, eine durch Fodichnia (Zoophycos, Dreginozoum, Rhizocorallium) dominierte Vergesellschaftung aus. Der ?fining-upward?-Trend innerhalb der untersuchten Schichtenfolge lässt auf eine Veränderung des Ablagerungsraumes von einer Hangfazies (Beckum-Schichten) in eine tiefere Beckenfazies (Vorhelm-Schichten) schließen