Recoil corrections in the hydrogen isoelectronic sequence

A version of the Bethe-Salpeter equation appropriate for calculating recoil corrections in highly charged hydrogenlike ions is presented. The nucleus is treated as a scalar particle of charge Z, and the electron treated relativistically. The known recoil corrections of order $m^2/M(Z\alpha)^4$ are derived in both this formalism and in NRQED

Effects of Magnetic System Unbalance on Magnetron Sputtering Characteristics

Deposition rate and ion current density distribution profiles at DC magnetron sputtering of Al, Ti and Cutargets were studied as functions of the process parameters and level of magnetron unbalance. Based onthe experimental data the distributions of the ion-to-atom ratio on the condensing surface under variousdeposition modes were calculated. It was established that in the case of DC magnetron sputtering the ionto-atom ratio on the condensing surface increased if the sputtering yield of the target’s material droppeddown. The minimal energy impact on the growing film and the most uniform distribution profile of theion-to-atom ratio were achieved by applying the I-type unbalanced magnetron system

Near-threshold femtosecond laser fabrication of one-dimensional subwavelength nanogratings on a graphite surface

Superimposed one-dimensional quasiperiodic gratings with multiple periods Λ≈110–800 nm well below or comparable to the pump laser wavelength of 744 nm, and ridge orientations perpendicular to the linear polarization of infrared femtosecond laser pulses, were fabricated after multiple near-threshold laser shots on a planar surface of quasimonocrystalline graphite in ambient airyesBelgorod State Universit

Band Crossing and Novel Low-Energy Behaviour in a Mean Field Theory of a Three-Band Model on a Cu--O lattice

We study correlation effects in a three-band extended Hubbard model of Cu -- O planes within the 1/N mean field approach, in the infinite U limit. We investigate the emerging phase diagram and discuss the low energy scales associated with each region. With increasing direct overlap between oxygen orbitals, $t_{pp} >0$, the solution displays a band crossing which, for an extended range of parameters, lies close to the Fermi level. In turn this leads to the nearly nested character of the Fermi surface and the resulting linear temperature dependence of the quasi-particle relaxation rate for sufficiently large T. We also discuss the effect of band crossing on the optical conductivity and comment on the possible experimental relevance of our findings.Comment: 12 pages, Latex-Revtex, 6 PostScript figures. Submitted to Phys. Rev.

A novel spin wave expansion, finite temperature corrections and order from disorder effects in the double exchange model

The magnetic excitations of the double exchange (DE) model are usually discussed in terms of an equivalent ferromagnetic Heisenberg model. We argue that this equivalence is valid only at a quasi--classical level -- both quantum and thermal corrections to the magnetic properties of DE model differ from any effective Heisenberg model because its spin excitations interact only indirectly, through the exchange of charge fluctuations. To demonstrate this, we perform a novel large S expansion for the coupled spin and charge degrees of freedom of the DE model, aimed at projecting out all electrons not locally aligned with core spins. We generalized the Holstein--Primakoff transformation to the case when the length of the spin is by itself an operator, and explicitly constructed new fermionic and bosonic operators to fourth order in 1/\sqrt{S}. This procedure removes all spin variables from the Hund coupling term, and yields an effective Hamiltonian with an overall scale of electron hopping, for which we evaluate corrections to the magnetic and electronic properties in 1/S expansion to order O(1/S^2). We also consider the effect of a direct superexchange antiferromagnetic interaction between core spins. We find that the competition between ferromagnetic double exchange and an antiferromagnetic superexchange provides a new example of an "order from disorder" phenomenon -- when the two interactions are of comparable strength, an intermediate spin configuration (either a canted or a spiral state) is selected by quantum and/or thermal fluctuations.Comment: 21 pages revtex, 11 eps figure

A Dynamic Theory of Resource Wars

We develop a dynamic theory of resource wars and study the conditions under which such wars can be prevented. Our focus is on the interaction between the scarcity of resources and the incentives for war in the presence of limited commitment. We show that a key parameter determining the incentives for war is the elasticity of demand. Our first result identifies a novel externality that can precipitate war: price-taking firms fail to internalize the impact of their extraction on military action. In the case of inelastic resource demand, war incentives increase over time and war may become inevitable. Our second result shows that in some situations, regulation of prices and quantities by the resource-rich country can prevent war, and when this is the case, there will also be slower resource extraction than the Hotelling benchmark (with inelastic demand). Our third result is that because of limited commitment and its implications for armament incentives, regulation of prices and quantities might actually precipitate war even in some circumstances where wars would not have arisen under competitive markets

Orientation, substructure, and optical properties of rutile films

The orientation, optical properties, and substructure of rutile films prepared by thermal and pulsed photon assisted oxidation of single crystal Ti films were investigated by transmission electron micros copy, optical spectroscopy, and high energy electron diffractionyesBelgorod State Universit

Elucidating suspended sediment dynamics in a glacierized catchment after an exceptional erosion event: The Djankuat catchment, Caucasus Mountains, Russia

Suspended sediment yields from glacierized catchments are often among the highest in the world, and their sediment dynamics can be highly variable. This study was undertaken in the 9.1 km2 glacierized catchment of the Djankuat River located in the Russian part of the Northern Caucasus. The outlet of the study catchment is a hydrological gauging station located at an altitude of 2635 m a.m.s.l. (‘N43◦12′31.71′′, E42◦44′05.93′′). The catchment includes a temperate valley glacier (area = 2.42 km2) and three smaller hanging glaciers, several moraine deposits, rock walls, and a large and expanding proglacial area. The main goal of our study was to assess the impact of an exceptional erosion event on 1st July 2015 (with an annual exceedance probability of less than 0.1%) on suspended sediment yields and the relative contributions of various sediment sources The work combined direct suspended sediment discharge measurements at the gauging station during five ablation seasons (2015–2019) with geomorphic mapping techniques based on detailed field observations and sediment source fingerprinting. Results show that mean annual suspended sediment yields reached 1118 t km− 2 year− 1 which is one of the highest measured estimates for any of the glacierized mountain rivers globally. About half of the annual suspended sediment flux was exported during a limited number (1–12% of the annual events) of extreme hydrological events. The sediments mobilized by bank and riverbed erosion within the new lower reach of a tributary channel which appeared after the breakthrough of a lateral moraine became the primary sediment source. It contributed over 50% of the suspended sediment on days with extreme rainfall. Contributions to the suspended sediment load from the glacier source were event-dependent and were only dominant (c. 60–70%) in the upper reaches of the proglacial area (first 800 m). The proglacial part of the study catchment with buried ice was the main sediment source (79%) during non-rain days