Conductance of p-n-p graphene structures with 'air-bridge' top gates

We have fabricated graphene devices with a top gate separated from the graphene layer by an air gap--a design which does not decrease the mobility of charge carriers under the gate. This gate is used to realise p-n-p structures where the conducting properties of chiral carriers are studied. The band profile of the structures is calculated taking into account the specifics of the graphene density of states and is used to find the resistance of the p-n junctions expected for chiral carriers. We show that ballistic p-n junctions have larger resistance than diffusive ones. This is caused by suppressed transmission of chiral carriers at angles away from the normal to the junction.Comment: to be published in Nano Letter

The specificity of interaction of the vyatich ethno-political association with its nomad neighbors in the IX-XI centuries

Introduction. Relevance and dating: one of the widely known stereotypes of the interaction between the Forest and the Steppe, considered as economic and social structures, is their innate rivalry and struggle.Materials and methods. An analysis of the data available to historical science suggests that following the stereotypes described above, when considering specific events and consequences of the interaction between the Vyatichi ethno-potestar association and its nomadic neighbors (near and distant) in the 9th-11th centuries, leads to obviously erroneous conclusions.Results. Source base: the sources here are, first of all, the results of archaeological research, which indicate numerous and clear signs of cultural, economic, administrative-military interaction. Applied methods: comparative-historical, diachronic-analytical using an interdisciplinary approach. In medieval Slavic history, one can find examples of different types of interaction between Slavic societies and their steppe neighbors: permanent struggle, principled war, neutral coexistence, as well as cooperation and interaction. One of the specific examples of this kind of interaction is the history of the emergence and development of the Upper Oka Vyatichi ethno-political association, which refutes most of the stereotypes stated above.Conclusion. The period considered in this report indicates, rather, the likely symbiotic reciprocity of the interaction of the Vyatichi community with representatives of the nomadic culture, which over time was destroyed by the military and political activity of the Kievan Rurikovich. The first centuries of the existence of this community demonstrate the enviable productivity and effectiveness of the interaction of the Vyatichi with their nomadic neighbors in various aspects of interaction, ranging from economic, political and cultural enrichment to possible cooperation in the field of animal husbandry

Density of states and zero Landau level probed through capacitance of graphene

We report capacitors in which a finite electronic compressibility of graphene dominates the electrostatics, resulting in pronounced changes in capacitance as a function of magnetic field and carrier concentration. The capacitance measurements have allowed us to accurately map the density of states D, and compare it against theoretical predictions. Landau oscillations in D are robust and zero Landau level (LL) can easily be seen at room temperature in moderate fields. The broadening of LLs is strongly affected by charge inhomogeneity that leads to zero LL being broader than other levels

Synthesis of Shell-Stabilized Nuclides in Fusion-Evaporation Reactions Induced by 48Ca, 50Ti, or 54Cr Projectiles

Production cross sections of nuclides in the vicinity of the closed neutron shell at N = 126 were measured in heavy-ion fusion reactions with 154Gd, 159Tb, 162Dy, and 165Hotargets. Even-Z beams of 48Ca, 50Ti, and 54Cr were chosen for this systematic survey. The resulting shell-stabilized residues vary in deformation and fissility, and the effect of these properties on the magnitude of the cross section is examined. Experimental data were collected at Texas A&M University Cyclotron Institute using the Momentum Achromat Recoil Spectrometer, which was operated as a particle separator. The measured cross sections cover a range from 12 mb to < 1 μb, decreasing in reactions induced by projectiles with successively higher Z. Model calculations, describing the progression of the fusion reaction from projectile-target collision to the ground-state product, were performed by dividing the process into three discrete steps of capture, fusion, and survival. The standard calculations overestimate the measured excitation functions by 0.5–2 orders of magnitude. The predictions are rectified by incorporating collective enhancement of level density into the model, suggesting that the fission probabilities in the deexcitation process of the compound nucleus exceed initial predictions. Hence, a rather weak influence of shell-stabilization on the production cross section of spherical nuclei is deduced. For 48Ca, 50Ti, and 54Cr reactions on the same target, the change in production-cross section is found to strongly depend on the difference between the fission barrier and neutron separation energy of the products and less so on the entrance channel

Impurities as a source of flicker noise in graphene

We experimentally study the effect of different scattering potentials on the flicker noise observed in graphene devices on silica substrates. The noise in nominally identical devices is seen to behave in two distinct ways as a function of carrier concentration, changing either monotonically or nonmonotonically. We attribute this to the interplay between long- and short-range scattering mechanisms. Water is found to significantly enhance the noise magnitude and change the type of the noise behaviour. By using a simple model, we show that water is a source of long-range scattering.Comment: 4 pages, 4 figure

ABOUT COMMON AND THEORETICAL INFORMATICS

In this article are considered the integrant importance of informatics and informational technologys includes the sciences and the humanities.There are a differences between scientifi c grounds of the various information orientations, which include physical informatics, bioinfomatics, technical and social informatics. Creation of a united theoretical base for these orientations is very problematical. The metodologically important issue of classifi cation different informatics is a part of the general informatics, the example of which are considered here