Temperature dependent relaxation of dipole-exchange magnons in yttrium iron garnet films

Low energy consumption enabled by charge-free information transport, which is free from ohmic heating, and the ability to process phase-encoded data by nanometer-sized interference devices at GHz and THz frequencies are just a few benefits of spin-wave-based technologies. Moreover, when approaching cryogenic temperatures, quantum phenomena in spin-wave systems pave the path towards quantum information processing. In view of these applications, the lifetime of magnons$-$spin-wave quanta$-$is of high relevance for the fields of magnonics, magnon spintronics and quantum computing. Here, the relaxation behavior of parametrically excited magnons having wavenumbers from zero up to $6\cdot 10^5 \mathrm{rad~cm}^{-1}$ was experimentally investigated in the temperature range from 20 K to 340 K in single crystal yttrium iron garnet (YIG) films epitaxially grown on gallium gadolinium garnet (GGG) substrates as well as in a bulk YIG crystal$-$the magnonic materials featuring the lowest magnetic damping known so far. As opposed to the bulk YIG crystal in YIG films we have found a significant increase in the magnon relaxation rate below 150 K$-$up to 10.5 times the reference value at 340 K$-$in the entire range of probed wavenumbers. This increase is associated with rare-earth impurities contaminating the YIG samples with a slight contribution caused by coupling of spin waves to the spin system of the paramagnetic GGG substrate at the lowest temperatures

Multi-staged deposition of trench-gate oxides for power MOSFETs

Here, silicon oxide was formed in a U-shaped trench of a power metal-oxide semiconductor field-effect transistor device by various processes. One SiO₂ formation process was performed in multiple steps to create a low-defect Si-SiO₂ interface, where first a thin initial oxide was grown by thermal oxidation followed by the deposition of a much thicker oxide layer by chemical vapor deposition (CVD). In a second novel approach, silicon nitride CVD was combined with radical oxidation to form silicon oxide in a stepwise sequence. The resulting stack of silicon oxide films was then annealed at temperatures between 1000 and 1100 °C. All processes were executed in an industrial environment using 200 mm-diameter (100)-oriented silicon wafers. The goal was to optimize the trade-off between wafer uniformity and conformality of the trenches. The thickness of the resulting silicon oxide films was determined by ellipsometry of the wafer surface and by scanning electron microscopy of the trench cross sections. The insulation properties such as gate leakage and electrical breakdown were characterized by current–voltage profiling. The electrical breakdown was found to be highest for films treated with rapid thermal processing. The films fabricated via the introduced sequential process exhibited a breakdown behavior comparable to films deposited by the common low-pressure CVD technique, while the leakage current at electric fields higher than 5 MV/cm was significantly lower

Linking Demographic Effects of Habitat Fragmentation Across Landscapes to Continental Source-Sink Dynamics

Forest fragmentation may cause increased brood parasitism and nest predation of breeding birds. In North America, nest parasitism and predation are expected to increase closer to forest edges because the brood-parasitic Brown-headed Cowbird(Molothrus ater) and generalist nest predators often enter the forest from adjoining developed (largely agricultural) habitats. Yet the abundance of brood parasites and nest predators at the patch scale may be strongly constrained by the total area of developed habitat at landscape scales. The scale and extent of landscape effects are unclear, however, because past studies were mostly conducted within local landscapes rather than across independent landscapes. We report replicated studies from 30 independent landscapes across 17 states of the United States that show that nest parasitism is strongly affected by fragmentation at a 20 km radius scale, equivalent to the maximum foraging range of cowbirds. Nest predation is influenced by both edge and landscape effects, and increases with fragmentation at a 10 km radius scale. Predation is additive to parasitism mortality, and the two together yield decreased population growth potential with increasing forest fragmentation at a 10 km radius scale for 20 of 22 bird species. Mapping of population growth potential across continental landscapes displays broad impacts of fragmentation on population viability and allows geographic prioritization for conservation

Do Millennials read books or blogs? Introducing a media usage typology of the internet generation

Purpose: Millennials, the Net Generation, and digital natives all represent the same, fervently discussed phenomenon, especially in the education sciences. As the terms suggest, the main idea behind this phenomenon is that the younger generation embraces new media far more comprehensively than the older generations. However, the literature is mostly based on anecdotal evidence. To date, surprisingly little empirical research exists on the media use of the "Internet Generation". In this paper, the authors aim to partially close this gap. In doing so, they focus especially on the use of social media. Design/methodology/approach: Active media use is a key element of social software and Web 2.0 and has the potential to affect the media industry on a fundamental level. Using a large-scale empirical study with over 800 participants, the authors identify three different subgroups of Millennials. Findings: The results indicate that, although participation in and identification with social media is generally high, Millennials are less homogeneous than the literature suggests. Furthermore, the traditional media still represent integral parts of the overall media portfolio. Originality/value: These results are valuable not only as a starting point for future research on the Millennials' media usage but also for media management practices in general. © Emerald Group Publishing Limited

Stainless Steel Valves with Enhanced Fatigue And Corrosion Performance Through Microstructure Optimization

In order to increase the energy efficiency of refrigerators, compressors, incorporating valves with new geometries have been developed over the past few years. In addition, higher stresses are increasingly placed upon the valve itself during operation. Hence, higher demands are set on the steel strip used to produce such valves. Today, compressor valves for refrigerators are mainly manufactured from hardened and tempered martensitic stainless steels. The main design criterion for the material selection is the endurance limit of the material under bending. However, impact loads and corrosive atmospheres often act additionally on the valve. To fulfil the increased demands for such new valves, the microstructure of the most commonly used stainless steel grade is refined. Through this method a new grade Zapp Super-Fatigue is developed, whereby the yield strength, ultimate tensile strength and bending fatigue are increased. In addition, the corrosion resistance of the material is also significantly increased. All the tests are performed with industrial scale processes and material. The properties are determined with samples taken from various production lots. Tensile properties as well as bending fatigue tests are performed on a strip with thickness typical for valves used for refrigerators. Current density potential measurements are conducted to confirm and explain the corrosion test results. Finally, the microstructure is characterized using a scanning electron microscopy with the electron back scatter diffraction method. For the first time, the microstructures of the most commonly used stainless steel and the improved grade Zapp Super-Fatigue are compared. It is demonstrated how the fatigue limit and the corrosion resistance of a martensitic stainless steel can be enhanced by tailoring the microstructure

Knowledge of previous tasks: task similarity influences bias in task duration predictions

Bias in predictions of task duration has been attributed to misremembering previous task duration and using previous task duration as a basis for predictions. This research sought to further examine how previous task information affects prediction bias by manipulating task similarity and assessing the role of previous task duration feedback. Task similarity was examined through participants performing two tasks 1 week apart that were the same or different. Duration feedback was provided to all participants (Experiment 1), its recall was manipulated (Experiment 2), and its provision was manipulated (Experiment 3). In all experiments, task similarity influenced bias on the second task, with predictions being less biased when the first task was the same task. However, duration feedback did not influence bias. The findings highlight the pivotal role of knowledge about previous tasks in task duration prediction and are discussed in relation to the theoretical accounts of task duration prediction bias