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Topological defects are ubiquitous, they manifest in a wide variety of systems such as liquid crystals, magnets or superconductors. The recent quest for non‐abelian anyons in condensed matter physics stimulates the interest for topological defects since they can be hosted in vortices in quantum magnets or topological superconductors. In addition to these vortex defects, this study proposes to investigate edge dislocations in 2D magnets as new building blocks for topological physics since they can be described as vortices in the structural phase field. It demonstrates the existence of higher order topological dislocations within the higher order moiré pattern of the van der Waals 2D magnet CrCl3 deposited on Au(111). Surprisingly, these higher order dislocations arise from ordinary simple edge dislocations in the atomic lattice of CrCl3. This study provide a theoretical framework explaining the higher order dislocations as vortices with a winding Chern number of 2. It is expected that these original defects can stabilize some anyons either in a 2D quantum magnet or within a 2D superconductor coupled to it. [ABSTRACT FROM AUTHOR]

An experimental study conducted in a wind tunnel on the mixing of moist air by a scaled wind turbine is presented. The experimental setup allows us to generate stable stratification conditions with respect to relative humidity and temperature in a closed-loop wind tunnel. The flow and its thermodynamic properties were characterized using a Cobra probe (a multi-hole pitot tube) and a sensor of local temperature and relative humidity, both used simultaneously to obtain vertical profiles. The flow and its stratification were measured downstream of a scaled rotor at two different streamwise distances (1 and 10 rotor diameters) and two Reynolds numbers based on the diameter of the wind turbine rotor (22 000 and 44 000, respectively). This was then compared to the inflow conditions. The wake mean structure and the humidity and temperature stratifications of the flow are found to be affected by the presence of the rotor. In particular, the stratification was always smaller one diameter downstream from the model (when compared to the empty test section case), and then was mostly recovered in the far wake (10 diameters downstream). This effect depended not only on the streamwise distance, but also on the Reynolds number of the flow. Finally, the bulk Richardson number Rb was found to be an appropriate parameter to quantify this effect. [ABSTRACT FROM AUTHOR]

Transition metal dichalcogenides (TMDs) display a rich variety of instabilities such as spin and charge orders, Ising superconductivity, and topological properties. Their physical properties can be controlled by doping in electric double‐layer field‐effect transistors (FET). However, for the case of single layer NbSe2, FET doping is limited to ≈1 × 1014 cm−2, while a somewhat larger charge injection can be obtained via deposition of K atoms. Here, by performing angle‐resolved photoemission spectroscopy, scanning tunneling microscopy, quasiparticle interference measurements, and first‐principles calculations it is shown that a misfit compound formed by sandwiching NbSe2 and LaSe layers behaves as a NbSe2 single layer with a rigid doping of 0.55–0.6 electrons per Nb atom or ≈6 × 1014 cm−2. Due to this huge doping, the 3 × 3 charge density wave is replaced by a 2 × 2 order with very short coherence length. As a tremendous number of different misfit compounds can be obtained by sandwiching TMDs layers with rock salt or other layers, this work paves the way to the exploration of heavily doped 2D TMDs over an unprecedented wide range of doping. [ABSTRACT FROM AUTHOR]

Large-eddy simulation is performed to study a katabatic jet along a convexly curved slope with a maximum angle of about 35.5°. The design of this numerical simulation of turbulent shear flow is discussed, and a qualitative assessment of the method is proposed. The katabatic flow is artificially generated by ground surface cooling, and a stable atmospheric boundary layer with constant stratification is considered as a reference state. A quantitative statistical analysis is used to describe the present turbulent flow, with a focus on the outer-layer shear of the katabatic jet, which extends about 50 m above the jet maximum. The Prandtl model for a katabatic jet is applied to the present results, and revisited versions of the model found in the literature are discussed, with an emphasis on specific momentum and turbulent heat diffusion. The vertical and downslope variability of the turbulent kinetic energy budget is also discussed, and it is shown that advection and production contributions in the downslope direction are far from negligible in katabatic flows along curved slopes. A specific effect that the convex curvature has on the katabatic jet is one of centrifugal deceleration and an increase of the flow's turbulent production and turbulent intensity in the outer-layer shear. A strong thickening of the outer layer is also observed. [ABSTRACT FROM AUTHOR]

Vortices in quantum condensates exist owing to a macroscopic phase coherence. Here we show, both experimentally and theoretically, that a quantum vortex with a well-defined core can exist in a rather thick normal metal, proximized with a superconductor. Using scanning tunneling spectroscopy we reveal a proximity vortex lattice at the surface of 50 nm—thick Cu-layer deposited on Nb. We demonstrate that these vortices have regular round cores in the centers of which the proximity minigap vanishes. The cores are found to be significantly larger than the Abrikosov vortex cores in Nb, which is related to the effective coherence length in the proximity region. We develop a theoretical approach that provides a fully self-consistent picture of the evolution of the vortex with the distance from Cu/Nb interface, the interface impedance, applied magnetic field, and temperature. Our work opens a way for the accurate tuning of the superconducting properties of quantum hybrids. [ABSTRACT FROM AUTHOR]

Just like insulators can present topological phases characterized by Dirac edge states, superconductors can exhibit topological phases characterized by Majorana edge states. In particular, one-dimensional topological superconductors are predicted to host zero-energy Majorana fermions at their extremities. By contrast, two-dimensional superconductors have a one-dimensional boundary which would naturally lead to propagating Majorana edge states characterized by a Dirac-like dispersion. In this paper we present evidences of onedimensional dispersive in-gap edge states surrounding a two-dimensional topological superconducting domain consisting of a monolayer of Pb covering magnetic Co-Si islands grown on Si(111). We interpret the measured dispersive in-gap states as a spatial topological transition with a gap closure. Our method could in principle be generalized to a large variety of heterostructures combining a Rashba superconductor with a magnetic layer in order to be used as a platform for engineering topological quantum phases. [ABSTRACT FROM AUTHOR]

Large-eddy simulation is performed to study a katabatic jet along a convexly curved slope with a maximum angle of about 35.5°. The design of this numerical simulation of turbulent shear flow is discussed, and a qualitative assessment of the method is proposed. The katabatic flow is artificially generated by ground surface cooling, and a stable atmospheric boundary layer with constant stratification is considered as a reference state. A quantitative statistical analysis is used to describe the present turbulent flow, with a focus on the outer-layer shear of the katabatic jet, which extends about 50mabove the jet maximum. The Prandtl model for a katabatic jet is applied to the present results, and revisited versions of the model found in the literature are discussed, with an emphasis on specific momentum and turbulent heat diffusion. The vertical and downslope variability of the turbulent kinetic energy budget is also discussed, and it is shown that advection and production contributions in the downslope direction are far from negligible in katabatic flows along curved slopes. A specific effect that the convex curvature has on the katabatic jet is one of centrifugal deceleration and an increase of the flow's turbulent production and turbulent intensity in the outer-layer shear. A strong thickening of the outer layer is also observed. [ABSTRACT FROM AUTHOR]

Deoxyribonucleic acid (DNA) is presented as a potential candidate to develop nanopackaging solutions in the field of microelectronics by a bottom-up approach. Such an approach could overcome the miniaturization limitations of the current top-down approaches. By its particular and unique properties of self-assembling and the capability to be functionalized, DNA is a versatile biological material that can be used in many different ways to build multiscale nanostructures and especially conductive nanowires (NWs). These NWs could be implemented as potential future nanoscale interconnections. [ABSTRACT FROM PUBLISHER]

With their attractive intrinsic properties, such as morphology, autoassembling properties, and tailorability, nano-objects could provide alternative and innovative routes to current microelectronics and nanoelectronics. Further insight on their electrical properties, especially in terms of statistics and reproducibility, as well as on their potential integration into silicon-based electronics is, however, often required to be able to fully exploit their potential. This paper proposes an innovative approach using a generic structure allowing the study of nano-objects electrical properties. Regarding the nano-objects integration, a homogeneous approach is presented with the in situ fabrication of atomic wires as a possible planar interconnection system. A heterogeneous approach is described as well with the characterization and preliminary integration of biological material, such as deoxyribonucleic acid-based nanowires or amyloid fibers. [ABSTRACT FROM PUBLISHER]

Superconducting correlations may propagate between two superconductors separated by a tiny insulating or metallic barrier, allowing a dissipationless electric current to flow. In the presence of a magnetic field, the maximum supercurrent oscillates and each oscillation corresponding to the entry of one Josephson vortex into the barrier. Josephson vortices are conceptual blocks of advanced quantum devices such as coherent terahertz generators or qubits for quantum computing, in which on-demand generation and control is crucial. Here, we map superconducting correlations inside proximity Josephson junctions using scanning tunnelling microscopy. Unexpectedly, we find that such Josephson vortices have real cores, in which the proximity gap is locally suppressed and the normal state recovered. By following the Josephson vortex formation and evolution we demonstrate that they originate from quantum interference of Andreev quasiparticles, and that the phase portraits of the two superconducting quantum condensates at edges of the junction decide their generation, shape, spatial extent and arrangement. Our observation opens a pathway towards the generation and control of Josephson vortices by applying supercurrents through the superconducting leads of the junctions, that is, by purely electrical means without any need for a magnetic field, which is a crucial step towards high-density on-chip integration of superconducting quantum devices. [ABSTRACT FROM AUTHOR]

This paper presents a flip-chip structure based on carbon nanotube (CNT) interconnected bumps for high-frequency applications. The CNT bumps are grown directly on gold coplanar lines using the plasma-enhanced chemical vapor deposition approach, and the CNT bumps are interconnected using a flip-chip bonder. DC and high-frequency measurements from flip-chip input to output are characterized and compared against electromagnetic simulation of CNT bumps and gold bumps. S-parameter transmission of -2.5 dB up to 40 GHz was obtained using CNT bumps in this experiment. Experimental transmission across the CNT bumps demonstrates the feasibility of using CNT bundles for future interconnects at smaller scale (few micrometers) and at even higher frequencies. This is the first work using CNT bumps for flip-chip structures and serves as a platform for future studies of CNT interconnects above 40 GHz. [ABSTRACT FROM PUBLISHER]

Electrical contacts between nanoengineered systems are expected to constitute the basic building blocks of future nanoscale electronics. However, the accurate characterization and understanding of electrical contacts at the nanoscale is an experimentally challenging task. Here, we employ low-temperature scanning tunneling spectroscopy to investigate the conductance of individual nanocontacts formed between flat Pb islands and their supporting substrates. We observe a suppression of the differential tunnel conductance at small bias voltages due to dynamical Coulomb blockade effects. The differential conductance spectra allow us to determine the capacitances and resistances of the electrical contacts which depend systematically on the island-substrate contact area. Calculations based on the theory of environmentally assisted tunneling agree well with the measurements. [ABSTRACT FROM AUTHOR]

We report on scanning-tunneling microscopy experiments in a charge-density wave (CDW) system allowing visually capturing and studying in detail the individual solitons corresponding to the selftrapping of just one electron. This "Amplitude Soliton" is marked by vanishing of the CDW amplitude and by the π shift of its phase. It might be the realization of the spinon—the long-sought particle (along with the holon) in the study of science of strongly correlated electronic systems. As a distinct feature we also observe one-dimensional Friedel oscillations superimposed on the CDW which develop independently of solitons. [ABSTRACT FROM AUTHOR]

Carbon nanotubes (CNTs) are a unique group of materials with high aspect ratio, mechanical and electrical properties, which are of great interests in the field of interconnects, and radio frequency applications. In order to incorporate CNTs into any of these applications successfully, one important issue that has to be resolved is the critical parameters (temperature and reactant gases) associated with the growth of the CNTs. As such, the effect of these growth requirements on the adjacent components should be studied. In this work, we examined specifically the effect of carbon nanotubes growth on the underlying metallization, in particular gold, dedicated for radio-frequency-based applications. The gold coplanar lines were annealed at 800°C in a plasma-enhanced chemical vapor deposition (PECVD) system to simulate the worst-case condition. The reflection and transmission parameters were analyzed using a probe station connected to a vector network analyzer. Carbon nanotubes grown on different barrier layers were also characterized using a scanning electron microscope and Raman spectroscopy to identify a suitable barrier layer for gold. Our results showed that it is promising to integrate carbon nanotubes grown using PECVD onto Au coplanar waveguide without degrading the S-parameters measurements up to 20 GHz. [ABSTRACT FROM PUBLISHER]

Abstract: The synthesis of two novel glycosyl-nucleoside fluorinated amphiphiles (GNFs) derived from the 2H,2H,3H,3H-perfluoro-undecanoyl hydrophobic chain is described. The GNF amphiphiles, which feature either β-d-glucopyranosyl or β-d-lactopyranosyl moieties linked to a thymine base via a 1,2,3 triazole linker, were prepared using a ‘double click’ chemistry route. Surface tension measurements, gelation properties, and TEM studies show that GNFs spontaneously assemble into supramolecular structures. Similarly to their hydrocarbon analogues (GNLs), the GNFs have unique gelation properties in water. A minimum hydrogelation concentration of 0.1% (w/w), was determined in the case of the β-d-glucopyranosyl derivative. Cell viability studies indicate that fluorocarbon GNF 5 was not toxic for human cells (Huh7), whereas hydrocarbon analogue GNL is toxic above 100μm. [Copyright &y& Elsevier]

The article presents a reflection on the knowledge that geographers had on the measurement of the surface area of France between 1570 and 1795. The different ways of defining a territory in the 18th century are examined, and the surface area of France as created by political economy at this period is analyzed. According to the article, the calculation of this surface between 1570 and 1792 was left to private individuals, and the role of the French state in the evolution of this number is discussed in the article.

Abstract: We have studied by scanning tunneling microscopy (STM) the two charge-density wave (CDW) transitions in NbSe3 on in situ cleaved plane. We could identify the three types of chains existing inside a single unit cell as well as characterize how both CDWs are distributed on these elementary chains. We also followed between 5 and 140K the temperature dependence of first-order CDW satellite spots, obtained from the Fourier transform of the STM images, to extract the surface critical temperatures . Whereas the high-temperature CDW appears to have comparable critical temperature to the bulk one, the low-T CDW transition occurs at , more than 15K above the bulk while at exactly the same wave number. A reasonable mechanism for such an unusually high surface enhancement is a softening of transverse phonon modes involved in the CDW formation. [Copyright &y& Elsevier]

Katabatic flows develop over every – even slightly – tilted terrain when a surface cooling occurs. These down-slope buoyancy-driven flows have the shape of an asymmetric wall jet with a wind maximum height (z=zj) of the order of a few meters, as it is generally observed in mountainous areas. This complex boundary-layer process does not respond to the classical Monin Obukov Similarity Therory (MOST) except, may be, in the lowest thin layer between the surface and zj/10. This flow configuration prevents from any MOST-applicability to fit field observations and even more to represent such processes in atmospheric models. As a similarity law for katabatic flows is yet to be formulated, it is of paramount importance to seek a deeper understanding of the physics of the processes involved. In this work we analyse a turbulence dataset collected during a field campaign held in November 2012 over the Grand Colon mountain slope (Belledonne ridge, French Alps). The main device consisted in 4 sonic anemometers installed at different heights at 1.0, 1.8, 4.0 and 6.3 m above the surface along a unique measuring mast. This mast was placed in the upper part of the slope, just below the summit, to capture the local generation of the flow. The gathered wind and temperature high-frequency measurements allowed us to carry out an in-depth analysis of the turbulence spectral characteristics within a katabatic flow. The analysis of both spectra and co-spectra reveal some specific turbulence characteristics of the katabatic flow. The spectral analyses confirmed that the frequency of the local energy injection generated by shear rely on height above the ground, except for heights close to zj. At these heights, since the shear vanishes, a deficit of local energy injection is observed on the spectra through an intermediate slope at the corresponding frequency. This does not respond to any known theory. The co-spectral analyses revealed that the distribution of the energy contribution per frequency, at each height of the wall jet, resulted from both positive and negative cross-correlations. The analysis of this distribution revealed a zone of progressive overlapping of these cross-correlations, which depends on z. It was further observed that small turbulent structures move up the wall jet from its lowest zone towards its highest zone. This phenomenon may result from a varying turbulent diffusivity that depends on the turbulent scale considered. Both the spectral and co-spectral analysis highlight the complexity of the turbulent processes within katabatic flows. [ABSTRACT FROM AUTHOR]

Based on Taylor series expansions for the filtered velocity field, we present an analytical study of the “Germano identity” used in the dynamic sub-grid scale (SGS) model for large eddy simulation (LES). We consider the case of explicit filtering defined in physical space and show that the choice of the length scale which characterizes the test SGS tensor T[sub ij] is a main issue in modeling the “Germano identity.” In the field of eddy-viscosity models, we demonstrate the accuracy of a Gaussian formulation l[sub fg][sup 2]=l[sub f][sup 2]+l[sub g][sup 2], based on a priori tests of fully developed pipe flow. More than a generalization of formal results [B. Vreman, B. Geurts, and H. Kuerten, J. Fluid Mech. 339, 357 (1997)], our study reveals constraints and limitations of the dynamic approach. © 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]

We study the unconventional superconducting correlations caused by a single isolated magnetic impurity in a conventional s-wave superconductor. Because of the local breaking of time-reversal symmetry, the impurity induces unconventional superconductivity, which is even in both space and spin variables but odd under time inversion. We derive an exact proportionality relation between the even-frequency component of the local electron density of states and the imaginary part of the odd-frequency local pairing function. By applying this relation to scanning tunneling microscopy spectra taken on top of magnetic impurities immersed in a Pb/Si(111) monolayer, we show experimental evidence of the occurrence of the odd-frequency pairing in these systems and explicitly extract its superconducting function from the data. [ABSTRACT FROM AUTHOR]

Polymorphisms in the Nicastrin (NCSTN) gene have recently been associated with familial early-onset Alzheimer''s disease (AD). The authors genotyped four NCTSN polymorphisms in a large cohort of 489 AD cases (including 158 sporadic early-onset AD cases and 95 familial early-onset AD cases) and 386 controls but failed to replicate the association between NCSTN haplotype B and AD. [Copyright &y& Elsevier]