Edge state effects in junctions with graphene electrodes

We consider plane junctions with graphene electrodes, which are formed by a single-level system ("molecule") placed between the edges of two single-layer graphene half planes. We calculate the edge Green functions of the electrodes and the corresponding lead self-energies for the molecular levels in the cases of semi-infinite single-layer electrodes with armchair and zigzag edges. We show two main effects: first, a peculiar energy-dependent level broadening, reflecting at low energies the linear energy dependence of the bulk density of states in graphene, and, second, the shift and splitting of the molecular level energy, especially pronounced in the case of the zigzag edges due to the influence of the edge states. These effects give rise to peculiar conductance features at finite bias and gate voltages.Comment: 8 pages, 8 figures, submitted to PR

Dielectric constants and phonon modes of amorphous hafnium aluminate deposited by metal organic chemical vapor deposition

Dielectric constants and long-wavelength optical phonon modes of amorphous hafnium aluminate films with a maximum aluminum content of 19 at. % are studied by infrared spectroscopic ellipsometry (IRSE). The hafnium aluminate films were prepared by metal organic chemical vapor deposition on silicon substrates. IRSE revealed one polar lattice mode and one impurity-type mode, which show all a systematic shift in frequency with varying Al content. The static dielectric constant decreases from 10.1 for 4.6 at. % Al to 8.1 for 19 at. % Al. The absolute values were found to be between 50% and 70% smaller than the values obtained from electrical measurements

Modelling of a radio frequency plasma bridge neutralizer (RFPBN)

A performance model of a radio frequency plasma bridge neutralizer was developed to calculate the electrical parameters and optimize the neutralizer design. Minimization of power losses and gas consumption, and a maximization of the neutralizer lifetime and the reliability of the system are requirements of all electric propulsion concepts and strongly determine their future application. The requirements of the neutralizer depend on mission profiles

advanced electric propulsion diagnostic tools at iom

Abstract Recently, we have set up an Advanced Electric Propulsion Diagnostic (AEPD) platform [1] , which allows for the in-situ measurement of a comprehensive set of thruster performance parameters. The platform utilizes a five-axis-movement system for precise positioning of the thruster with respect to the diagnostic heads. In the first setup (AEPD1) an energy-selective mass spectrometer (ESMS) and a miniaturized Faraday probe for ion beam characterization, a telemicroscope and a triangular laser head for measuring the erosion of mechanical parts, and a pyrometer for surface temperature measurements were integrated. The capabilities of the AEPD1 platform were demonstrated with two electric propulsion thrusters, a gridded ion thruster RIT 22 (Airbus Defence & Space, Germany, [13]) and a Hall effect thruster SPT 100D EM1 (EDB Fakel, Russia, [1] , [4] ), in two different vacuum facilities

Proton‐Radiation Tolerant All‐Perovskite Multijunction Solar Cells

Funder: European Research Council; Id: http://dx.doi.org/10.13039/501100000781Funder: Engineering and Physical Sciences Research Council; Id: http://dx.doi.org/10.13039/501100000266Funder: European Union's Horizon 2020Abstract: Radiation‐resistant but cost‐efficient, flexible, and ultralight solar sheets with high specific power (W g−1) are the “holy grail” of the new space revolution, powering private space exploration, low‐cost missions, and future habitats on Moon and Mars. Herein, this study investigates an all‐perovskite tandem photovoltaic (PV) technology that uses an ultrathin active layer (1.56 µm) but offers high power conversion efficiency, and discusses its potential for high‐specific‐power applications. This study demonstrates that all‐perovskite tandems possess a high tolerance to the harsh radiation environment in space. The tests under 68 MeV proton irradiation show negligible degradation (22%. Using high spatial resolution photoluminescence (PL) microscopy, it is revealed that defect clusters in GaAs are responsible for the degradation of current space‐PV. By contrast, negligible reduction in PL of the individual perovskite subcells even after the highest dose studied is observed. Studying the intensity‐dependent PL of bare low‐gap and high‐gap perovskite absorbers, it is shown that the VOC, fill factor, and efficiency potentials remain identically high after irradiation. Radiation damage of all‐perovskite tandems thus has a fundamentally different origin to traditional space PV

Managerial power in the German model: the case of Bertelsmann and the antecedents of neoliberalism

Our article extends the research on authoritarian neoliberalism to Germany, through a history of the Bertelsmann media corporation – sponsor and namesake of Germany’s most influential neoliberal think-tank. Our article makes three conceptual moves. Firstly, we argue that conceptualizing German neoliberalism in terms of an ‘ordoliberal paradigm’ is of limited use in explaining the rise and fall of Germany’s distinctive socio-economic model (Modell Deutschland). Instead, we locate the origins of authoritarian tendencies in the corporate power exercised by managers rather than in the power of state-backed markets imagined by ordoliberals. Secondly, we focus on the managerial innovations of Bertelsmann as a key actor enmeshed with Modell Deutschland. We show that the adaptation of business management practices of an endogenous ‘Cologne School’ empowered Bertelsmann’s postwar managers to overcome existential crises and financial constraints despite being excluded from Germany’s corporate support network. Thirdly, we argue that their further development in the 1970s also enabled Bertelsmann to curtail and circumvent the forms of labour representation associated with Modell Deutschland. Inspired by cybernetic management theories that it used to limit and control rather than revive market competition among its workforce, Bertelsmann began to act and think outside the postwar settlement between capital and labour before the settlement’s hotly-debated demise since the 1990s