Effect of an InP/In0.53_{0.53}Ga0.47_{0.47}As Interface on Spin-orbit Interaction in In0.52_{0.52}Al0.48_{0.48}As/In0.53_{0.53}Ga0.47_{0.47}As Heterostructures

We report the effect of the insertion of an InP/In$_{0.53}$Ga$_{47}$As Interface on Rashba spin-orbit interaction in In$_{0.52}$Al$_{0.48}$As/In$_{0.53}$Ga$_{0.47}$As quantum wells. A small spin split-off energy in InP produces a very intriguing band lineup in the valence bands in this system. With or without this InP layer above the In$_{0.53}$Ga$_{47}$As well, the overall values of the spin-orbit coupling constant $\alpha$ turned out to be enhanced or diminished for samples with the front- or back-doping position, respectively. These experimental results, using weak antilocalization analysis, are compared with the results of the $\mathbf{k\cdot p}$ theory. The actual conditions of the interfaces and materials should account for the quantitative difference in magnitude between the measurements and calculations.Comment: Submitted for publication; v2 to adjust Eq.6; v3 to correct the figure file name; v4, a revised version accepted for publication in Phys. Rev.

Superfluid gap formation in a fermionic optical lattice with spin imbalanced populations

We investigate the attractive Hubbard model in infinite spatial dimensions at quarter filling. By combining dynamical mean-field theory with continuous-time quantum Monte Carlo simulations in the Nambu formalism, we directly deal with the superfluid phase in the population imbalanced system. We discuss the low energy properties in the polarized superfluid state and the pseudogap behavior in the vicinity of the critical temperature.Comment: 4 pages, 1 figure, To appear in J. Phys.: Conf. Ser. for SCES201

Competition between Spin-Orbit Interaction and Zeeman Coupling in Rashba 2DEGs

We investigate systematically how the interplay between Rashba spin-orbit interaction and Zeeman coupling affects the electron transport and the spin dynamics in InGaAs-based 2D electron gases. From the quantitative analysis of the magnetoconductance, measured in the presence of an in-plane magnetic field, we conclude that this interplay results in a spin-induced breaking of time reversal symmetry and in an enhancement of the spin relaxation time. Both effects, due to a partial alignment of the electron spin along the applied magnetic field, are found to be in excellent agreement with recent theoretical predictions.Comment: 4 figures and 4 page

Use of Combined Hartree-Fock-Roothaan Theory in Evaluation of Lowest States of K [Ar]4s^0 3d^1 and Cr+ [Ar]4s^0 3d^5 Isoelectronic Series Over Noninteger n-Slater Type Orbitals

By the use of integer and noninteger n-Slater Type Orbitals in combined Hartree-Fock-Roothaan method, self consistent field calculations of orbital and lowest states energies have been performed for the isoelectronic series of open shell systems K [Ar]4s^0 3d^1 2(D) (Z=19-30) and Cr+ [Ar] 4s^0 3d^5 6(S) (Z=24-30). The results of calculations for the orbital and total energies obtained from the use of minimal basis sets of integer- and noninteger n-Slater Type Orbitals are given in tables. The results are compared with the extended-basis Hartree-Fock computations. The orbital and total energies are in good agreement with those presented in the literature. The results are accurately and considerably can be useful in the application of non-relativistic and relativistic combined Hartree-Fock-Roothaan approach for heavy atomic systems.Comment: 11 pages, 6 tables, 2 figures. submitte

Spin-orbit induced interference in polygon-structures

We investigate the spin-orbit induced spin-interference pattern of ballistic electrons travelling along any regular polygon. It is found that the spin-interference depends strongly on the Rashba and Dresselhaus spin-orbit constants as well as on the sidelength and alignment of the polygon. We derive the analytical formulae for the limiting cases of either zero Dresselhaus or zero Rashba spin-orbit coupling, including the result obtained for a circle. We calculate the nonzero Dresselhaus and Rashba case numerically for the square, triangle, hexagon, and circle and discuss the observability of the spin-interference which can potentially be used to measure the Rashba and Dresselhaus coefficients.Comment: 17 pages, 4 figure

First-order quantum phase transition in the orthogonal-dimer spin chain

We investigate the low-energy properties of the orthogonal-dimer spin chain characterized by a frustrated dimer-plaquette structure. When the competing antiferromagnetic couplings are varied, the first-order quantum phase transition occurs between the dimer and the plaquette phases, which is accompanied by nontrivial features due to frustration: besides the discontinuity in the lowest excitation gap at the transition point, a sharp level-crossing occurs for the spectrum in the plaquette phase. We further reveal that the plateau in the magnetization curve at 1/4 of the full moment dramatically changes its character in the vicinity of the critical point. It is argued that the first-order phase transition in this system captures some essential properties found in the two-dimensional orthogonal-dimer model proposed for $\rm SrCu_2(BO_3)_2$.Comment: 7 pages, submitted to Phys. Rev.

Office paper recyclability: fibrous characteristics

Recyclability is the ability of a material to reacquire the same properties it had originally. The aim of this work was to verify the recyclability of three printing and writing papers, from the characteristics of their fibers after two recycles. Three ECF bleached kraft eucalyptus commercial bond papers from Argentina and Brazil were studied (A, B, C). The papers were repulped and refined using different levels and intensities of energy (1st recycle). Laboratory sheets were produced, and they were repulped and refined again (2nd recycle). The microscopic characteristics of repulped papers were obtained by automatic equipment based on image analysis. Differences found in the behavior of the different samples can be explained by fiber parameters. The fiber length was significantly different in the three papers (A > B > C) and globally decreased in the second recycle (about 6%). Sample A had the highest initial fiber length and length/width, but it largely decreased with refining conditions in the 1st recycle (length fall 12%, generating fines by cutting), whereas it fall 9% between the 1st and 2nd recycles, and nothing with refining conditions in the 2nd recycle. Sample B fall by 5% with refining conditions in the 1st recycle, and 9% between the 1st and the 2nd recycle, but suffered few alteration in the second recycle. Fiber length of sample C was unaffected by refining conditions and only decreased 9% between the 1st and 2nd recycles. In all cases, the generated fines increased lightly with refining in the first recycle, but were two-fold higher in the second recycle than in the first one. The fiber coarseness of the 3 samples was similar in the first recycle, but decreases significantly in the 2nd recycleFil: Benitez, Julieta Beatriz. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Instituto de Materiales de Misiones. Universidad Nacional de Misiones. Facultad de Cs.exactas Químicas y Naturales. Instituto de Materiales de Misiones; ArgentinaFil: Koga, Mariza E. T.. Instituto de Pesquisas Tecnologicas de Sao Paulo; BrasilFil: Otero D'Almeida, Maria L.. Instituto de Pesquisas Tecnologicas de Sao Paulo; BrasilFil: Felissia, Fernando Esteban. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Instituto de Materiales de Misiones. Universidad Nacional de Misiones. Facultad de Cs.exactas Químicas y Naturales. Instituto de Materiales de Misiones; ArgentinaFil: Park, Song W.. Universidade de Sao Paulo; BrasilFil: Area, Maria Cristina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Instituto de Materiales de Misiones. Universidad Nacional de Misiones. Facultad de Cs.exactas Químicas y Naturales. Instituto de Materiales de Misiones; Argentin

On the thermodynamic stability and structural transition of clathrate hydrates

Gas mixtures of methane and ethane form structure II clathrate hydrates despite the fact that each of pure methane and pure ethane gases forms the structure I hydrate. Optimization of the interaction potential parameters for methane and ethane is attempted so as to reproduce the dissociation pressures of each simple hydrate containing either methane or ethane alone. An account for the structural transitions between type I and type II hydrates upon changing the mole fraction of the gas mixture is given on the basis of the van der Waals and Platteeuw theory with these optimized potentials. Cage occupancies of the two kinds of hydrates are also calculated as functions of the mole fraction at the dissociation pressure and at a fixed pressure well above the dissociation pressure

Phase diagram of orbital-selective Mott transitions at finite temperatures

Mott transitions in the two-orbital Hubbard model with different bandwidths are investigated at finite temperatures. By means of the self-energy functional approach, we discuss the stability of the intermediate phase with one orbital localized and the other itinerant, which is caused by the orbital-selective Mott transition (OSMT). It is shown that the OSMT realizes two different coexistence regions at finite temperatures in accordance with the recent results of Liebsch. We further find that the particularly interesting behavior emerges around the special condition $U=U'$ and J=0, which includes a new type of the coexistence region with three distinct states. By systematically changing the Hund coupling, we establish the global phase diagram to elucidate the key role played by the Hund coupling on the Mott transitions.Comment: 4 pages, 6 figure

High Voltage CMOS Control Interface for Astronomy - Grade Charged Coupled Devices

The Pan-STARRS telescope consists of an array of smaller mirrors viewed by a Gigapixel arrays of CCDs. These focal planes employ Orthogonal Transfer CCDs (OTCCDs) to allow on-chip image stabilization. Each OTCCD has advanced logic features that are controlled externally. A CMOS Interface Device for High Voltage has been developed to provide the appropiate voltage signal levels from a readout and control system designated STARGRASP. OTCCD chip output levels range from -3.3V to 16.7V, with two different output drive strenghts required depending on load capacitance (50pF and 1000pF), with 24mA of drive and a rise time on the order of 100ns. Additional testing ADC structures have been included in this chip to evaluate future functional additions for a next version of the chip.Comment: 13 pages, 17 gigure