SwePub - search: L773:0587 4246 OR L773:1898 79...

Enumeration	Reference	Cover	Find
1.	Appelgren, Patrik, et al. (author) Studies of Electrically-Exploded Conductors for Electric Armour Applications 2009 In: Acta Physica Polonica. A. - 0587-4246 .- 1898-794X. ; 115:6, s. 1072-1074 Journal article (peer-reviewed)abstract This paper presents experimental studies of current interaction with static copper rods. The results of the static experiments are used to discuss the effects responsible for the disruption of shaped-charge jets in electric armour. These effects include ohmic heating of, and current diffusion into, the rod as well as radial magnetic forces.
2.	Archibald, M., et al. (author) Characterization of Break in Quantum Grid 2020 In: Acta Physica Polonica. A. - : Institute of Physics, Polish Academy of Sciences. - 0587-4246 .- 1898-794X. ; 138:3, s. 383-391 Journal article (peer-reviewed)
3.	Baranska, M., et al. (author) Off-Axis Electron Holography of Magnetic Nanostructures : Magnetic Behavior of Mn Rich Nanoprecipitates in (Mn,Ga) As System 2017 In: Acta Physica Polonica. A. - : Polish Physical Society. - 0587-4246 .- 1898-794X. ; 131:5, s. 1406-1408 Journal article (peer-reviewed)abstract The Lorentz off-axis electron holography technique is applied to study the magnetic nature of Mn rich nanoprecipitates in (Mn,Ga) As system. The effectiveness of this technique is demonstrated in detection of the magnetic field even for small nanocrystals having an average size down to 20 nm.
4.	Bauch, S., et al. (author) Some Applications of Generalized Euler Characteristic of Quantum Graphs and Microwave Networks 2021 In: Acta Physica Polonica. A. - 0587-4246 .- 1898-794X. ; 140:6, s. 525-531 Journal article (peer-reviewed)abstract In this article we continue to explore the possibilities offered by our discovery that one of the main graph and network characteristic, the generalized Euler characteristic iG, can be determined from a graph/network spectrum. We show that using the generalized Euler characteristic iG the number of vertices with Dirichlet \|VD\| boundary conditions of a family of graphs/networks created on the basis of the standard quantum graphs or microwave networks can be easily identified. We also present a new application of the generalized Euler characteristic for checking the completeness of graphs/networks spectra in the low energy range.
5.	Berggren, Karl-Fredrik, 1937-, et al. (author) Electrical Resonance Circuits as Analogs to Quantum Mechanical Billiards 2006 In: Acta Physica Polonica. A. - 0587-4246 .- 1898-794X. ; 109, s. 33-42 Journal article (peer-reviewed)abstract We propose that a two-dimensional electric network may be used for fundamental studies of wave function properties, transport, and related statistics. Using Kirchhoff 's current law and the jw-method we find that the network is analogous to a discretized Schrodinger equation for quantum billiards and clots. Thus the complex electric potentials play the role of quantum rnechanical wave functions.
6.	Bidulsky, Robert, et al. (author) Interparticle Neck Connections in Innovative Insulated Iron Powder Compounds 2015 In: Acta Physica Polonica A. - 0587-4246 .- 1898-794X. ; 128:4, s. 647-650 Journal article (peer-reviewed)abstract Goal of the present paper is the analysis of the interparticle neck connections in a system made of insulated iron powder compounds with different additions of an Al-Mg-Si-Cu alloy (0.25, 0.5 and 0.75 wt%). The introduction of the aluminium alloy powder has been made in order to improve the mechanical properties, evaluated as thetransverse rupture strength, without decreasing the agnetic properties (evaluated in terms of iron loss and coercivity force). The fracture analysis of investigated systems puts into evidence the breaking of interparticle neck connections. Heat treatment (at the temperature of 500C) contributes to the early stages of interparticle neck developments. The chosen aluminium alloy presents a sort of pre-sintering behaviour at 500C, with the possibility of mass-transport processes around the insulated iron powder compounds. The air heat treatment applied aims at providing an increase in the mechanical behaviour of the material, with a final good rigidity after the cooling process. Fracture surfaces and transverse rupture strength values show that, at 500 MPa, the strength and the area related to the inter-particle necks can be correlated to the occasional broken insulated point-to-point surfacesthat hinder the development of inter-particles necks.
7.	Buda, A., et al. (author) Network Structure of Phonographic Market with Characteristic Similarities between Artists 2013 In: Acta Physica Polonica. A. - 0587-4246 .- 1898-794X. ; 123:3, s. 547-552 Journal article (peer-reviewed)abstract We investigate relations between bestselling artists in last decade on phonographic market and from perspective of listeners by using the Social Network Analyzes. Starting network is obtained from the matrix of correlations between the world's bestselling artists by considering the synchronous time evolution of weekly record sales. This method reveals the structure of phonographic market, but we claim that it has no impact on people who see relationship between artists and music genres. We compare sale (based on correlation of record sales) or popularity (based on data mining of the record charts) networks with similarity (obtained mainly from survey within music experts' opinion) and find no significant relations. We postulate that non-laminar phenomena on this specific market introduce turbulence to how people view relations of artists.
8.	Budkowski, Andrzej, et al. (author) Structures in multi-component polymer films : their formation, observation and applications in electronics and biotechnology 2009 In: Acta Physica Polonica. A. - Warsaw : Polish Academy of Sciences, Institute of Physics. - 0587-4246 .- 1898-794X. ; 115:2, s. 435-440 Journal article (peer-reviewed)abstract Several strategies to form multicomponent films of functional polymers, with micron, submicron and nanometer structures, intended for plastic electronics and biotechnology are presented. These approaches are based on film deposition from polymer solution onto a rotating substrate (spin-casting), a method implemented already on manufacturing lines. Film structures are determined with compositional (nanometer) depth profiling and (submicron) imaging modes of dynamic secondary ion mass spectrometry, near-field scanning optical microscopy (with submicron resolution) and scanning probe microscopy (revealing nanometer features). Self-organization of spin-cast polymer mixtures is discussed in detail, since it o®ers a one-step process to deposit and align simultaneously domains, rich in di®erent polymers, forming various device elements: (i) Surface segregation drives self-stratification of nanometer lamellae for solar cells and anisotropic conductors. (ii) Cohesion energy density controls morphological transition from lamellar (optimal for encapsulated transistors) to lateral structures (suggested for light emitting diodes with variable color). (iii) Selective adhesion to substrate microtemplates, patterned chemically, orders lateral structures for plastic circuitries. (iv) Submicron imprints of water droplets (breath figures) decorate selectively micron-sized domains, and can be used in devices with hierarchic structure. In addition, selective protein adsorption to regular polymer micropatterns, formed with soft lithography after spin-casting, suggests applications in protein chip technology. An approach to reduce lateral blend film structures to submicron scale is also presented, based on (annealed) films of multicomponent nanoparticles
9.	Das, S., et al. (author) Spatial Resolution Test of a Beam Profile Monitoring System for the Double Electrostatic Ion Storage Ring 2014 In: Acta Physica Polonica. A. - 0587-4246 .- 1898-794X. ; 125:1, s. 13-17 Journal article (peer-reviewed)abstract A beam profile monitoring system based on the imaging of low energy electrons created when the ion beam impinges on a metal plate was built to monitor the beam profile and to cover the wide range of beam intensities and energies for the DESIREE (Double ElectroStatic Ion Ring ExpEriment) beam line diagnostics. The spatial resolution of the system was tested with different beams of various energies and was found to be around 2 mm. A significant steering effect on the ion beam before hitting the metallic foil was observed at low energies.
10.	Durakiewicz, T., et al. (author) Quest for Band Renormalization and Self-Energy in Correlated f-Electron Systems 2010 In: Acta Physica Polonica. A. - 0587-4246 .- 1898-794X. ; 117:2, s. 264-267 Journal article (peer-reviewed)abstract Coexisting low-energy scales are observed in f-electron materials. The information about some of low-energy scales is imprinted in the electron self-energy, which can be measured by angle-resolved photoemission (ARPES). Such measurements in d-electron materials over the last decade were based on high energy- and momentum-resolution ARPES techniques used to extract the self-energy information from measured spectra. Simultaneously, many-body theoretical approaches have been developed to find a link between the self-energy and many-body interactions. Here we show the transcription of such methods from d-electrons to f-electrons by presenting the first example of low energy scales in the f-electron material USb2, measured with synchrotron-based ARPES. The proposed approach will help in answering the fundamental questions about the complex nature of the heavy fermion state.
11.	Faraz, S. M., et al. (author) Voltage- and Frequency-Dependent Electrical Characteristics and Interface State Density of Ni/ZnO Schottky Diodes 2022 In: Acta Physica Polonica. A. - : POLISH ACAD SCIENCES INST PHYSICS. - 0587-4246 .- 1898-794X. ; 141:2, s. 99-104 Journal article (peer-reviewed)abstract Frequency and voltage dependent electrical characteristics are reported for Ni/ZnO Schottky diodes. Schottky diodes are realized from nano-structured ZnO thin films grown by DC magnetron sputtering. Electrical characterizations are performed by current-voltage (I-V), capacitance-voltage (C-V) and conductance-voltage (G/omega-V) measurements. The diode parameters are extracted, such as barrier height (phi(B)), ideality factor (n) and carrier concentration (N-D). The diodes exhibited a non-linear rectifying behaviour with a barrier height of 0.68 eV and an ideality factor greater than unity. Charge transport mechanism and possible reasons responsible for non-idealities are investigated. The density of interface states (N-SS) below the conduction band are extracted from the measured values of I-V and C-V as a function of E-C - E-SS. From E-C- 0.51 to E-C - 0.64 eV below the conduction band edge, the interface state density N-SS is found to be in the range 1.74 x 10(12)-1.87 x 10(11) eV cm. The interface states density obtained from capacitance-frequency (C-f) characteristics varied from 0.53 x 10(12)-0.12 x 10(12) eV cm from E-C 0.82 eV to E-C 0.89 eV below the conduction band. A complete description of current transport and interface properties is important for the realization of good quality Schottky diodes and for the design and implementation of high performance electronic circuits and systems.
12.	Hessmo, B., et al. (author) Entangled states in interferometry 2002 In: Acta Physica Polonica. A. - 0587-4246 .- 1898-794X. ; 101:1, s. 37-46 Journal article (peer-reviewed)abstract We show how some entangled quantum states can be used to improve interferometric measurements. We describe why Schrodinger-cat states are very sensitive to relative-phase shifts and why relative-phase states as described by A. Luis and L.L. Sanchez-Soto resolve the interval [0, 2pi] well. We also describe how the quantum concept of well-defined relative-phase and the classical visibility of an interference pattern are related.
13.	Hussain, Mushtaque, et al. (author) Effect of Post Growth Annealing on the Structural and Electrical Properties of ZnO/CuO Composite Nanostructures 2014 In: Acta Physica Polonica. A. - : Polish Academy of Sciences, Institute of Physics. - 0587-4246 .- 1898-794X. ; 126:3, s. 849-854 Journal article (peer-reviewed)abstract In the present work, ZnO/CuO composite nanostructures have been grown on fluorine doped tin oxide coated glass substrate by aqueous chemical growth method. To observe the effect of post growth annealing (500 degrees C, 1 min) on the structural properties of ZnO nanorods scanning electron microscope and X-ray diffraction techniques have been utilized. SEM images of post growth annealed (post growth annealed) sample reveal that the average diameter of ZnO NRs has considerably increased in comparison with as grown sample. Moreover after post growth annealing the ZnO NRs showed more clearly hexagonal wurtzite structure. Beside this the NRs are also uniform and well aligned with a high aspect ratio of similar to 10. In XRD pattern the strongly intense (002) peak of the post growth annealing sample suggest that the crystal quality of the NRs have also been improved significantly. Since the structural improvement have a significant impact on charge transport properties as well, therefore the effect of post growth annealed has also been investigated by the electrical characterization of ZnO/CuO based heterojunction. The current-voltage measurements of the post growth annealed sample showed improvement in the current in comparison with as grown sample. The impedance study has also confirmed that the post growth annealed has influence on the electrical properties. The presented post growth annealed heterojunction of ZnO/CuO may have space in applications like sensors and oxide based diodes in the devices fabrication.
14.	Ievtushenko, A, et al. (author) Ultraviolet Detectors Based on ZnO : N Thin Films with Different Contact Structures 2008 In: Acta Physica Polonica. A. - 0587-4246 .- 1898-794X. ; 114:5, s. 1123-1129 Journal article (peer-reviewed)abstract Al/ZnO:N/Al and Ni/ZnO:N/Al diode photodetectors fabricated by do magnetron sputtering of ZnO:N films on p-Si substrates are studied. The photocurrent-to-dark current ratio equal to 250 at lambda = 390 nm and the time constant of photoresponse about 10 mu s for Al/ZnO:N/Al structures with 4 mu m interdigital spacing was achieved. The Ni/ZnO:N/Al diode structure has the rectification ratio approximate to 10(2) at bias 1 V, the maximal responsivity about 0.1 A/W is observed at 365 nm, and the measured time constant of photoresponse is about 100 ns.
15.	Ivanov, VY, et al. (author) Microwave-induced delocalization of excitons in ternary compounds of II-VI and III-V semiconductors 2003 In: Acta Physica Polonica. A. - 0587-4246 .- 1898-794X. ; 103:6, s. 559-566 Journal article (peer-reviewed)abstract In this work we employ technique of optically detected cyclotron resonance for evaluation of the role of localization processes in CdTe/CdMnTe and CdMnTe/CdMgTe quantum well structures. From microwave-induced changes of excitonic emissions we evaluate magnitude of potential fluctuations (Stokes shift), correlate optically detected cyclotron resonance results with the results of time-resolved experiments and discuss nature of recombination processes in the limit of a strong localization.
16.	Jaskorzynska, Bozena, et al. (author) Nonlinear upconversion-rate in Er-doped fibers 2001 In: Acta Physica Polonica. A. - 0587-4246 .- 1898-794X. ; 99:1, s. 147-153 Journal article (peer-reviewed)abstract Energy transfer between excited rare-earth ions has been widely used for realizing upconversion lasers and also recognized as a gain limiting factor in high-concentration Er-doped amplifiers. The energy transfer leads to upconversion of the excitation which for randomly distributed (not clustered) ions is called homogeneous upconversion. It was commonly assumed that the rate of homogeneous upconversion is a linear function of the population inversion N-2. However, recently published Monte Carlo simulations predict that the homogeneous upconversion rate is a nonlinear function of N-2 and that it, moreover, depends on the pump and signals rates. In this paper we review some of our experimental results confirming those predictions. We also propose a statistical, analytical model describing the observed homogeneous upconversion behavior in Er-doped fibers.
17.	Khoptyar, D., et al. (author) Steady-state and switch-off behavior of upconversion in Er-doped fibers 2003 In: Acta Physica Polonica. A. - 0587-4246 .- 1898-794X. ; 103:03-feb, s. 207-210 Journal article (peer-reviewed)abstract By measuring the metastable and the upconverted fluorescence in Er-doped fibers we determine rate of homogeneous upconversion as a function of the population inversion. The results confirm the prediction of our statistical model that at the same population inversion the upconversion rates under the steady-state and the switch-off conditions are different. The larger rate of the steady state upconversion is attributed to the pump enhanced, redistribution of the excitation energy.
18.	Kim, B. H., et al. (author) Development of a PbWO4 Detector for Single-Shot Positron Annihilation Lifetime Spectroscopy at the GBAR Experiment 2020 In: Acta Physica Polonica. A. - 0587-4246 .- 1898-794X. ; 137:2, s. 122-125 Journal article (peer-reviewed)abstract We have developed a PbWO4 (PWO) detector with a large dynamic range to measure the intensity of a positron beam and the absolute density of the ortho-positronium (o-Ps) cloud it creates. A simulation study shows that a setup based on such detectors may be used to determine the angular distribution of the emission and reflection of o-Ps to reduce part of the uncertainties of the measurement. These will allow to improve the precision in the measurement of the cross-section for the (anti)hydrogen formation by (anti)proton-positronium charge exchange and to optimize the yield of antihydrogen ion which is an essential parameter in the GBAR experiment.
19.	Kovtun, Yu.V., et al. (author) Characteristics of VHF Discharge N2 Plasma in Uragan-2M Stellarator 2020 In: Acta Physica Polonica A. - : Institute of Physics, Polish Academy of Sciences. - 1898-794X .- 0587-4246. ; 138:4, s. 632-637 Journal article (peer-reviewed)
20.	Kowalski, B. J., et al. (author) Mn Contribution to the Valence Band of Ga0.98Mn0.02Sb : A Photoemission Study 2022 In: Acta Physica Polonica. A. - : Institute of Physics Polish Academy of Sciences. - 0587-4246 .- 1898-794X. ; 141:3, s. 175-179 Journal article (peer-reviewed)abstract The contribution of the Mn 3d states to the valence band of Ga0.98Mn0.02Sb, an important factor determining the properties of this system, including the mechanism responsible for the magnetic characteristics, has been revealed by photoelectron spectroscopy. The resonant photoemission experiment, carried out for photon energies close to the Mn 3d -> 3p excitation, allowed us to identify the spectral feature corresponding to emission from the Mn 3d states. The scanning of the valence band along the [100] direction of the Brillouin zone, by the angle-resolved photoemission experiment, showed that these states contributed to a dispersionless structure at the binding energy of 3.6 eV (with respect to the Fermi energy). The revealed shape of the Mn 3d contribution is consistent with the supposition that the p-d exchange interaction prevails as a mechanism supporting ferromagnetism in Ga1-xMnxSb.
21.	Kret, S., et al. (author) FIB Method of Sectioning of III-V Core-Multi-Shell Nanowires for Analysis of Core/Sell Interfaces by High Resolution TEM 2017 In: Acta Physica Polonica. A. - : Polish Physical Society. - 0587-4246 .- 1898-794X. ; 131:5, s. 1332-1335 Journal article (peer-reviewed)abstract The core-multishell wurtzite structure (In, Ga) As-(Ga, Al) As-(Ga, Mn) As semiconductor nanowires have been successfully grown on GaAs(111) B substrates using MBE technique. The nanowires cores were grown with gold eutectic catalyser in vapour-liquid-solid growth mode. The double shell overgrowth, on the side facets of nanowires, was performed using lower substrate temperature (about 400 degrees C, and 230 degrees C, for (Ga, Al) As, and (Ga, Mn) As shell growth, respectively). The polytypic ordering, defects, chemistry and geometric perfection of the core and the shells have been analysed at atomic level by advanced transmission electron microscope techniques with the use of axial and longitudinal section of individual nanowires prepared by focused ion beam. High quality cross-sections suitable for quantitative transmission electron microscope analysis have been obtained and enabled analysis of interfaces between the core and the shells with near atomic resolution. All investigated shells are epitaxial without misfit dislocations at the interface. Some of the shells thicknesses are not symmetric, which is due to the shadowing effects of neighbouring nanowires and directional character of the elemental fluxes in the MBE growth process.
22.	Kurasov, Pavel, 1964- (author) Always Detectable Eigenfunctions on Metric Graphs 2021 In: Acta Physica Polonica. A. - 0587-4246 .- 1898-794X. ; 140:6, s. 510-513 Journal article (peer-reviewed)abstract It is proven that Laplacians with standard vertex continuous on metric trees and with standard and Dirichlet conditions on arbitrary metric graphs possess an infinite sequence of simple eigenvalues with the eigenfunctions not equal to zero in any non-Dirichlet vertex.
23.	Kurasov, Pavel (author) Inverse Problems for Quantum Graphs : Recent Developments and Perspectives 2011 In: Acta Physica Polonica. A. - 0587-4246 .- 1898-794X. ; 120:6A, s. A132-A141 Journal article (peer-reviewed)abstract An introduction into the area of inverse problems for the Schrodinger operators on metric graphs is given. The case of metric finite trees is treated in detail with the focus on matching conditions. For graphs with loops we show that for almost all matching conditions the potential on the loop is not determined uniquely by the Titchmarsh-Weyl function. The class of all admissible potentials is characterized.
24.	Kurasov, Pavel, 1964- (author) On Magnetic Boundary Control for Metric Graphs 2023 In: Acta Physica Polonica. A. - 0587-4246 .- 1898-794X. ; 144:6, s. 456-461 Journal article (peer-reviewed)abstract It is investigated how magnetic boundary control can be used to solve inverse problems for Schrödinger operators on metric graphs. Explicit examples show that such reconstruction is sometimes possible, starting from a single contact vertex in the graph.
25.	Kurasov, Pavel (author) On the inverse problem for quantum graphs with one cycle 2009 In: Acta Physica Polonica. A. - 0587-4246 .- 1898-794X. Journal article (peer-reviewed)
26.	Kurasov, Pavel (author) On the Spectral Gap for Laplacians on Metric Graphs 2013 In: Acta Physica Polonica. A. - : Institute of Physics, Polish Academy of Sciences. - 0587-4246 .- 1898-794X. ; 124:6, s. 1060-1062 Journal article (peer-reviewed)abstract We discuss lower and upper estimates for the spectral gap of the Laplace operator on a finite compact connected metric graph. It is shown that the best lower estimate is given by the spectral gap for the interval with the same total length as the original graph. An explicit upper estimate is given by generalizing Cheeger's approach developed originally for Riemannian manifolds.
27.	Kurasov, Pavel (author) Surgery of Graphs : M-Function and Spectral Gap 2017 In: Acta Physica Polonica. A. - 0587-4246 .- 1898-794X. ; 132:6, s. 1666-1671 Journal article (peer-reviewed)abstract We discuss behaviour of the spectral gap for quantum graphs when two metric graphs are glued together. It appears that precise answer to this question can be given using a natural generalisation of the Titchmarsh-Weyl M-functions.
28.	Kurasov, Pavel (author) Understanding Quantum Graphs 2019 In: Acta Physica Polonica. A. - 0587-4246 .- 1898-794X. ; 136:5, s. 797-802 Journal article (peer-reviewed)abstract Current understanding of spectral asymptotics for quantum graphs is described. It is discussed how these results can be applied to inverse problems. In particular it is analysed whether the inverse spectral problem has a unique solution in the spirit of classical Ambartsumian theorem: a complete overview is provided.
29.	Ławniczak, M., et al. (author) Euler Characteristic of Graphs and Networks 2021 In: Acta Physica Polonica. A. - 0587-4246 .- 1898-794X. ; 139:3, s. 323-327 Journal article (peer-reviewed)abstract The Euler characteristic chi = vertical bar V vertical bar - vertical bar E vertical bar is an important topological characteristic of graphs and networks. Here, vertical bar V vertical bar and vertical bar E vertical bar denote the number of vertices and edges of a graph or a network. It has been shown in [Phys. Rev. E 101, 052320 (2020)] that the Euler characteristic can be determined from a finite sequence of the lowest eigenenergies lambda(1), ..., lambda(N) of a simple quantum graph. We will test this finding numerically, using chaotic graphs with vertical bar V vertical bar = 8 vertices. We will consider complete (fully connected) and incomplete realizations of 8-vertex graphs. The properties of the Euler characteristic will also be tested experimentally using the sequence of the lowest resonances of the 5-vertex microwave network. We will show that the Euler characteristic chi can be used to reveal whether the graph is planar or not.
30.	Legut, D., et al. (author) Interference Effects in T-MOKE Spectra of Fe Thin Films at the 3p Edges - Theory and Experiment 2015 In: Acta Physica Polonica. A. - 0587-4246 .- 1898-794X. ; 127:2, s. 466-468 Journal article (peer-reviewed)abstract We present combined first-principle calculations and experimental results of the transversal magneto-optical Kerr effect (T-MOKE) of thin Fe films across the 3p edges using linearly polarized synchrotron radiation. We show that the experimental T-MOKE spectra at the 3p edges of Fe exhibit clear signals that are strongly influenced by interference effects. Ab initio calculated T-MOKE asymmetry spectra confirm the importance of interference effects. The comparison of experimental with calculated spectra reveals some differences that we attribute to metal/metal interface roughness that is not taken into account in the calculations.
31.	Legut, D., et al. (author) Magnetic exchange interactions and estimation of T-N in CsNiF3 from first principles 2008 In: Acta Physica Polonica. A. - 0587-4246 .- 1898-794X. ; 113:1, s. 503-506 Journal article (peer-reviewed)abstract The CsNiF3 has been for long time studied as a prototype of quasi-1D planar ferromagnetic system. At very low temperature the studied system is insulator and therefore the magnetic exchange interactions should decay very rapidly. We treated the magnetic exchange coupling within the Heisenberg model for the nearest neighbor interaction between the antiferromagnetically coupled Ni-chains. The influence of up to the second-nearest neighbors on the ferromagnetic exchange coupling along the Ni-chains was determined. The exchange interactions were calculated for the experimental volume by the density functional theory, within the all-electron approach using the local density approximation for the exchange and correlation. The Neel temperature was calculated by means of the mean-field theory and by the random-phase approximation method.
32.	Lindblom, A., et al. (author) First Trials with a 45 GW Cable-Based Pulsed-Power Generator 2009 In: Acta Physica Polonica. A. - 0587-4246 .- 1898-794X. ; 115:6, s. 976-977 Journal article (peer-reviewed)abstract The output from narrow-band high-power microwave (HPM) sources, such as the virtual cathode oscillator (vircator) and the magnetically insulated line oscillator (MILO), is strongly dependent on the voltage pulse feed. A rectangular, flat-top voltage pulse can be achieved by the use of a transmission line as a pulse-forming unit. The development in high-voltage cable technology has made them useful as parts of high-voltage and high-power generator systems. The generator is designed to deliver a 200 ns voltage pulse of 500 kV into a 10 Omega unmatched load with an electric power of 25 GW. The generator has an impedance of 2 Q. The primary energy storage of the generator consists of a 50 kV, 20 U capacitor bank. The 50 kV is discharged into a transformer that charges a pulse-forming line to 550 kV. When charged, the pulse-forming line is discharged into the load via a spark gap. This paper presents results from initial testing of the generator.
33.	Misiorny, Maciej, 1982, et al. (author) Spin and charge transport in a magnetic tunnel junction with magnetic impurities embedded in the tunnel barrier 2015 In: Acta Physica Polonica A. - 0587-4246 .- 1898-794X. ; 128:2, s. 196-199 Journal article (peer-reviewed)abstract Electronic transport in a nanoscopic magnetic tunnel junction with magnetic particles or magnetic impurity atoms/molecules embedded in the barrier is studied theoretically. The impurity Hamiltonian includes magnetic anisotropy of easy axis type with additional perpendicular term. The description takes into account both elastic tunneling processes as well as inelastic processes associated with a flip of electron spin.
34.	Niang, S., et al. (author) Accumulation of Positrons from a LINAC Based Source 2020 In: Acta Physica Polonica. A. - 0587-4246 .- 1898-794X. ; 137:2, s. 164-166 Journal article (peer-reviewed)abstract The GBAR experiment aims to measure the gravitational acceleration of antihydrogen (H) over bar. It will use (H) over bar (+) ions formed by the interaction of antiprotons with a dense positronium cloud, which will require about 1010 positrons to produce one (H) over bar (+). We present the first results on the positron accumulation, reaching 3.8 +/- 0.4x10(8) e(+) collected in 560 s.
35.	Nikolaenko, Y. M., et al. (author) Fast bolometric response of bulk La0.7Sr0.3MnO3 electroceramic structures 2000 In: Acta Physica Polonica. A. - 0587-4246 .- 1898-794X. ; 97:6, s. 991-995 Journal article (peer-reviewed)abstract We report on the performance of a microwave electroceramic bolometer of hybrid La0.7Sr0.3MnO3/Al2O3 (0.2 x 2 x 4 mm(3)) structure. The estimated thermal resistance of the bulk ceramic manganite film-single crystal sapphire interface is about 500 K/W at room temperature. This resistance is the main thermal barrier in the heat sink system and has been found to be slightly dependent on temperature, When compared with the high-ire superconducting bolometers, the La0.7Sr0.3MnO3 microwave electroceramic bolometer works in a more wide temperature range, from 77 K to 330 K, excluding the narrow temperature interval at the metal-insulator phase transition (T = 230 K). The microwave electroceramic bolometer sensitivity and the time constant at room temperature have been found to be 0.1 V/W and 100 ms, respectively. To improve the bolometer performance the point contact has been fabricated by a break junction technique. The optimization of a microwave electroceramic bolometer design brought to a considerable improvement of basic bolometer characteristics. The microwave sensitivity was about 0.3 V/W and the time constant was less than 100 ns.
36.	Persson, Clas, et al. (author) Morphology and Magnetic Coupling in ZnO:Co and ZnO:Ni Co-Doped with Li 2011 In: Acta Physica Polonica. A. - 0587-4246 .- 1898-794X. ; 119:2, s. 95-98 Journal article (peer-reviewed)abstract Zn0.95Co0.05O and Zn0.97Ni0.03O nanorods, prepared by a solvothermal method, show intriguing morphology and magnetic properties when co-doped with Li. At low and moderate Li incorporation (below 10 and 3 at.% Li in the Co- and Ni-doped samples, respectively) the rod aspect ratio is increased and room temperature ferromagnetic properties are enhanced, whereas the ferromagnetic coupling in Zn0.97Ni0.03O is decreased for Li concentrations > 3 at.%. First-principles theoretical analyses demonstrate that Li co-doping has primarily two effect 3 in bulk Zn1-xMxO (with M = Co or Ni). First, the Li-on-Zn acceptors increase the local magnetic moment by depopulating the M 3d minority spin-states. The magnetic coupling is Ruderman-Kittel-Kasuya-Yosida-like both without and with Li co-doping. Second, Li-on-Zn prefer to be close to the M atoms to compensate the M-O bonds and to locally depopulate the 3d states, and this will help forming high aspect nanostructures. The observed room temperature ferromagnetism in Li co-doped Zn1-xMxO nanorods can therefore be explained by the better rod morphology in combination with ionizing the magnetic M atoms.
37.	Płomińska, Anna, et al. (author) Dynamical Aspects of Magnetic Switching in a Single Molecule-Based Spin Valve 2018 In: Acta Physica Polonica A. - 0587-4246 .- 1898-794X. ; 133:3, s. 555-557 Journal article (peer-reviewed)abstract The dynamics of the current-induced magnetic switching process is theoretically studied in a spin-valve device containing a single magnetic molecule of spin S 1. The analysis is performed by using the real-time diagrammatic technique in the sequential electron tunneling regime. In particular, we show that the magnetic moment of a molecule can be reversed also in the presence of intrinsic spin relaxation processes. Moreover, we discuss how the process of magnetic switching depends on a transport bias voltage as well as on some key parameters of the device.
38.	Przado, D., et al. (author) The influence of metastabilities on the luminescence in the Cu(In,Ga)Se2 solar cells 2007 In: Acta Physica Polonica. A. - 0587-4246 .- 1898-794X. ; 112:2, s. 183-189 Journal article (peer-reviewed)abstract Photoluminescence and electroluminescence spectra of the absorber layer in ZnO/CdS/Cu(In,Ga)Se-2 solar cells were measured. Their dependence on temperature, excitation intensity and applied voltage were studied. Electroluminescence measurements were used to investigate light- and bias-induced metastabilities in the absorber of the cells. We showed that metastable changes of defect distributions, which produce an effect on the electrical characteristics of ZnO/CdS/Cu(In,Ga)Se2 material, affect also the luminescence yield. The dependence of the intensity and shape of the electroluminescence spectra on the state of the sample is observed. These results fit well into the theoretical calculations of Lany and Zunger model showing that divacancy complex (V-Sc-V-Cu) is responsible for metastable changes observed in ZnO/CdS/Cu (In, Ga) Se-2-based solar cells. We conclude that during light soaking or/and forward bias the probability of nonradiative recombination is decreased.
39.	Rusz, Jan, et al. (author) Magnetic circular dichroism in electron microscopy 2008 In: Acta Physica Polonica. A. - 0587-4246 .- 1898-794X. ; 113:1, s. 599-604 Journal article (peer-reviewed)abstract Although the analogies between the electron energy loss spectra and X-ray absorption spectra were recognized long ago, the possibility to observe the magnetic circular dichroism in the electron microscope was demonstrated only recently. This technique combines the atom specificity with the high spatial resolution of the transmission electron microscope. Being a very young technique, there are still many open questions concerning the optimization of the signal to noise ratio. In this paper we study the dichroic signal dependence on the sample thickness, acceleration voltage and incoming beam tilt angle of bcc-Fe and fcc-Ni.
40.	Shevchenko, E. A., et al. (author) AlGaN Quantum Well Heterostructures for Mid-Ultraviolet Emitters with Improved Room Temperature Quantum Efficiency 2014 In: Acta Physica Polonica. A. - : POLISH ACAD SCIENCES INST PHYSICS. - 0587-4246 .- 1898-794X. ; 126:5, s. 1140-1142 Journal article (peer-reviewed)abstract We report on optical studies of exciton localization and recombination kinetics in two single 2.2 nm thick AlxGa1-xN/Alx+0.1Ga0.9-xN quantum well structures (x = 0.55 and 0.6) grown by plasma assisted molecular beam epitaxy on a c-sapphire substrate. Strong localization potential inherent for both the quantum well and barrier regions results in merging of the quantum well and barrier emission spectra into a single broad line centered at 285 nm (x = 0.55) and 275 nm (x = 0.6). Time-resolved photoluminescence measurements revealed surprising temperature stability of the photoluminescence decay time constant (approximate to 400 ps) relevant to the recombination of the quantum well localized excitons. This observation implies nearly constant quantum efficiency of the quantum well emission in the whole range from 4.6 to 300 K.
41.	Shtepliuk, I., et al. (author) Phase Field Modeling of the Zn1-xCdxO Solid Solutions 2014 In: Acta Physica Polonica. A. - : POLISH ACAD SCIENCES INST PHYSICS. - 0587-4246 .- 1898-794X. ; 126:5, s. 1079-1082 Journal article (peer-reviewed)abstract The analysis of spinodal decomposition in the Zn1-xCdxO ternary alloy was carried out by means of the nonlinear Cahn-Hilliard equation. Interaction parameter as a function of composition x was provided by valence force field simulations and was used in this analysis. The morphological patterns for the ternary alloys with different Cd content (x = 5, 10, 50%) were experimentally obtained using the semi-implicit Fourier-spectral method. The simulated microstructure evolution Zn0.95Cd0.05O demonstrates that the microstructure having a form of bicontinuous worm-like network is evolved with the progress of aging. An effect of the phase-field mobility and the gradient energy on the microstructure evolution of the Zn1-xCdxO alloys is discussed. It was found that the higher driving force for the decomposition in the higher Cd content film results in a higher decomposition rate revealed by the simulations. The temporal evolution of the simulated Zn0.95Cd0.05O microstructure is in good agreement with experimental results, which have been obtained for this solid solution.
42.	Skubic, Björn, et al. (author) Exchange coupling and exchange bias in FM/AFM bilayers for a fully compensated AFM interface 2009 In: Acta Physica Polonica. A. - 0587-4246 .- 1898-794X. ; 115:1, s. 25-29 Journal article (peer-reviewed)abstract We address the interlayer coupling in a ferromagnet/antiferromagnet bilayer where the interface of theantiferromagnet is fully compensated. We discuss the role of di®erent types of exchange interaction for theinterlayer coupling and exchange bias. We propose two types of corrections to the ideal Heisenberg Hamiltonianwhich may explain exchange bias. The ¯rst is a correction for the angular dependence of the exchange interactionsand the second a correction due to magnetostriction and interface imperfections. The ¯rst correction contributes toan anisotropy at the interface and favors either parallel or perpendicular coupling across the interface. The secondcorrection contributes to the exchange bias. Our analysis is based on atomic spin dynamics simulations, and ourresults show that small corrections to the ideal Heisenberg Hamiltonian may have macroscopic consequences insystems with frustrated interatomic interactions.
43.	Suchodolskis, A., et al. (author) Photoemission and optical spectroscopy of i-ZnMgEr quasicrystal 2005 In: Acta Physica Polonica. A. - 0587-4246 .- 1898-794X. ; 107:2, s. 412-419 Journal article (peer-reviewed)abstract The results of photoemission and optical studies of icosahedral single-grain ZnMgEr quasicrystals are presented. Synchrotron radiation photoemission measurements were performed on in situ cleaved samples at 10(-10) mbar pressure and low, 140-150 K temperature. The valence band photoemission spectra measured reveal a simple metal-type valence band of icosahedral ZnMgEr with a distinct Fermi edge cut-off and with a sharp pseudogap feature. The photoemission spectra of shallow Mg 2p and Zn 3d core levels indicate a coordination shift of Mg 2p spin-orbit doublet and an oscillating dependence of Zn 3d photoemission line components on the photon energy within the hv = 20-160 eV range investigated. The optical response of icosahedral ZnMgEr, a dispersion of the dielectric function, was measured by the spectroscopic ellipsometry technique in the 0.5-5.0 eV spectral range. The optical spectra of the quasicrystal indicate the Drude-type optical response superimposed with a peak of interband optical transitions. The interband optical transitions can be modelled with the pseudogap parameters which agree with those deduced in an analysis of the photoemission valence band spectra.
44.	Szewczyk, R., et al. (author) Open Source Implementation of Different Variants of Jiles-Atherton Model of Magnetic Hysteresis Loops 2018 In: Acta Physica Polonica. A. - 0587-4246 .- 1898-794X. ; 133:3, s. 654-656 Journal article (peer-reviewed)abstract Jiles-Atherton model is one of the most advanced and most popular models of magnetic hysteresis loop. However, this model is considering different physical phenomena and computational issues. As a result, cross-validation of the results of modelling performed by different authors became difficult. For this reason, the open-source MATLAB/OCTAVE based implementation of Jiles-Atherton model was developed. Proposed implementation covers isotropic model of magnetic hysteresis loops as well as uniaxial and grain oriented electrical steel anisotropy. Moreover, the corrections proposed by Venkataraman together with different approaches to derivative of the anhysteretic magnetization are considered. Developed library is freely available together with the examples of magnetic hysteresis loops. As a result, it can be the base for further development of Jiles-Atherton model for better understanding of magnetization process as well as modelling the inductive components.
45.	Tai, Cheuk-Wai (author) Synthesis and characterization of carbon nanotubes decorated with gold nanoparticles 2010 In: Acta Physica Polonica. A. - 0587-4246 .- 1898-794X. ; 118:3, s. 483-486 Journal article (peer-reviewed)abstract In presented work we report results of simple and viable method for producing Au/CNT composites. Chemicalcomposition and crystallographic structure of the Au/CNT composites was confirmed by X-ray diffractionmeasurements, while transmission and scanning electron microscopy were used to characterize the morphology ofnanocrystals as well as the distribution of nanocrystals in the composite. The obtained particles with relativelysmall diameter (less than 9 nm) were found to be spatially well dispersed on the carbon nanotubes. The densityof attached Au–nanoparticles is not sufficient, and cannot be improved by simple increasing gold loading.
46.	Valcheva, E., et al. (author) Influence of well-width fluctuations on the electronic structure of GaN/AlxGa1-xN multiquantum wells with graded interfaces 2007 In: Acta Physica Polonica. A. - 0587-4246 .- 1898-794X. ; 112:2, s. 395-400 Journal article (peer-reviewed)abstract Experimental and computation results based on chemical composition assessment of metal-organic chemical vapour deposition grown undoped GaN/AlxGa1-xN multiquantum well structures in the low composition limit of x = 0.07 and wide wells demonstrate composition fluctuations in the barrier layers which lead to large-scale nonuniformities and inequivalence of the different wells. As a consequence the experimental photoluminescence spectra at low temperature show a double peak structure indicative of well-width fluctuations by one lattice parameter (2 monolayers).
47.	Vasallo, Beatriz G., et al. (author) Monte carlo analysis of impact ionization in isolated-gate InAs/AlSb high electron mobility transistors 2011 In: Acta Physica Polonica A. - 0587-4246 .- 1898-794X. ; 119:2, s. 222-224 Conference paper (peer-reviewed)abstract We perform a physical analysis of the kink effect in InAs/AlSb high electron mobility transistors by means of a semiclassical 2D ensemble Monte Carlo simulator. Due to the small bandgap of InAs, InAs/AlSb high electron mobility transistors are very susceptible to suffer from impact ionization processes, with the subsequent hole transport through the structure, both implicated in the kink effect. When the drain-to-source voltage VDS is high enough for the onset of impact ionization, holes generated tend to pile up at the gate-drain side of the buffer. This occurs due to the valence-band energy barrier between the buffer and the channel. Because of this accumulation of positive charge, the channel is further opened and the drain current I D increases, leading to the kink effect in the I-V characteristics.
48.	Willander, Magnus, et al. (author) Optical properties of InAs quantum dots 2002 In: Acta Physica Polonica. A. - : Polish Academy of Sciences Warsaw. - 0587-4246 .- 1898-794X. ; 102:4-5, s. 567-576 Journal article (peer-reviewed)abstract InAs quantum dots grown on GaAs substrate were investigated by optical spectroscopy. We particularly emphasized on the photoluminescence intensity, the stability of the photoluminescence intensity versus temperatures and wavelength of the InAs dot emission at various thermal treatments and different structures. We found that hydrogen can strongly passivate nonradiative centers without causing any structure degradation, and both n- and p-type modulation doping can reduce the decrease in the photoluminescence intensity when the sample temperature increases from the helium temperature to room temperature. The emission wavelength and the efficiency of the InAs quantum dots can also be manipulated by choosing proper materials of cap layer.
49.	Wolska, A., et al. (author) Study of the Local Environment of Mn Ions Implanted in GaSb 2010 In: Acta Physica Polonica. A. - 0587-4246 .- 1898-794X. ; 117:2, s. 286-292 Journal article (peer-reviewed)abstract The first attempts to establish an implantation process leading to formation of ferromagnetic inclusions inside the GaSb matrix are presented. Gallium antimonide containing ferromagnetic MnSb precipitations is considered as a promising material for novel spintronic applications. It is possible to obtain such inclusions during the molecular beam epitaxy (MBE) growth. However, for commercial application it would be also important to find an optimal way of producing this kind of inclusions by Mn ions implantation. In order to achieve this goal, several parameters of implantation and post annealing procedures were tested. The ion energy was kept at 10 keV or 150 keV and four different ion doses were applied, as well as various annealing conditions. The analysis of X-ray absorption spectra allowed to estimate the local atomic order around Mn atoms. Depending on the implantation energy and annealing processes, the manganese oxides or manganese atoms located in a heavily defected GaSb matrix were observed. The performed analysis helped in indicating the main obstacles in formation of MnSb inclusions inside the GaSb matrix by Mn ion implantation.
50.	Wolska, A., et al. (author) XANES studies of Mn K and L-3,L-2 edges in the (Ga,Mn) As layers modified by high temperature annealing 2008 In: Acta Physica Polonica. A. - 0587-4246 .- 1898-794X. ; 114:2, s. 357-366 Journal article (peer-reviewed)abstract Ga1-xMnx As is commonly considered as a promising material for microelectronic applications utilizing the electron spin. One of the ways that allow increasing the Curie temperature above room temperature is to produce second phase inclusions. In this paper Gal-,Mn.As samples containing precipitations of ferromagnetic MnAs are under consideration. We focus on the atomic and electronic structure around the Mn atoms relating to the cluster formation. The changes in the electronic structure of the Mn, Ga and As atoms in the (Ga,Mn)As layers after high temperature annealing were determined by X-ray absorption near edge spectroscopy. The experimental spectra were compared with the predictions of ab initio full multiple scattering theory using the FEFF 8.4 code. The nominal concentration of the Mn atoms in the investigated samples was 6% and 8%. We do not observe changes in the electronic structure of Ca and As introduced by the presence of the Mn atoms. We find, in contrast, considerable changes in the electronic structure around the Mn atoms. Moreover, for the first time it was possible to indicate the preferred interstitial positions of the Mn atoms.

Skapa referenser, mejla, bekava och länka

Permalink

Träfflista för sökning "L773:0587 4246 OR L773:1898 794X "

Refine your search

Year