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Author Novoselov, K.S.; Geim, A.K.; Dubonos, S.V.; Cornelissens, Y.G.; Peeters, F.M.; Maan, J.C.
Title Quenching of the Hall effect in localised high magnetic field regions Type A1 Journal article
Year 2002 Publication Physica. E: Low-dimensional systems and nanostructures Abbreviated Journal Physica E
Volume 12 Issue 1/4 Pages 244-247
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract We report the suppression of the Hall effect in a mesoscopic Hall cross with a strong magnetic field only in the centre and vanishingly small outside, The local magnetic field is produced by placing Dy pillar on top of a structure with a high-mobility two-dimensional electron gas. The effect is found to be due to a sharp increase of the number of back-scattered and quasi-localised electron orbits. The possibility of localising electrons inside the magnetic inhomogeneity region is discussed. (C) 2002 Elsevier Science B.V. All rights reserved.
Address
Corporate Author Thesis
Publisher North-Holland Place of Publication Amsterdam Editor
Language Wos 000175206300061 Publication Date 2002-10-15
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1386-9477; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 2.221 Times cited 3 Open Access
Notes Approved Most recent IF: 2.221; 2002 IF: 1.107
Call Number (down) UA @ lucian @ c:irua:94939 Serial 2804
Permanent link to this record
 
 
Author Huang, W.; Zhang, X.-B.; Tu, J.; Kong, F.; Ning, Y.; Xu, J.; Van Tendeloo, G.
Title Synthesis and characterization of graphite nanofibers deposited on nickel foams Type A1 Journal article
Year 2002 Publication Physical chemistry, chemical physics Abbreviated Journal Phys Chem Chem Phys
Volume 4 Issue 21 Pages 5325-5329
Keywords A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract Nickel foams were used as catalysts to dissociate acetylene and deposit carbon atoms. Graphite nanofibers with distinct structures were developed at 550degreesC with nickel foams pretreated with hydrogen. HREM observations showed that the graphite layers of the nanofibers were aligned at a certain angle to the fiber axis. It is suggested that hydrogen treatment and metal catalysts have a tremendous impact on the yields and microstructures of the graphite nanofibers. The growth mechanism of these fish-bone graphite nanofibers is also discussed.
Address
Corporate Author Thesis
Publisher Place of Publication Cambridge Editor
Language Wos 000178635300016 Publication Date 2002-10-17
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1463-9076;1463-9084; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 4.123 Times cited 20 Open Access
Notes Approved Most recent IF: 4.123; 2002 IF: 1.838
Call Number (down) UA @ lucian @ c:irua:94938 Serial 3411
Permanent link to this record
 
 
Author Chang, K.; Xia, J.B.; Wu, H.B.; Feng, S.L.; Peeters, F.M.
Title Quantum-confined magneto-Stark effect in diluted magnetic semiconductor coupled quantum wells Type A1 Journal article
Year 2002 Publication Applied physics letters Abbreviated Journal Appl Phys Lett
Volume 80 Issue 10 Pages 1788-1790
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract The magneto-Stark effect in a diluted magnetic semiconductor (DMS) coupled quantum well (CQW) induced by an in-plane magnetic field is investigate theoretically. Unlike the usual electro-Stark effects, in a DMS CQW the Lorenz force leads to a spatially separated exciton. The in-plane magnetic field can shift the ground state of the magnetoexciton from a zero in-plane center of mass (CM)/momentum to a finite CM momentum, and render the ground state of magnetoexciton stable against radiative recombination due to momentum conservation. (C) 2002 American Institute of Physics.
Address
Corporate Author Thesis
Publisher American Institute of Physics Place of Publication New York, N.Y. Editor
Language Wos 000174181800036 Publication Date 2002-07-26
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0003-6951; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 3.411 Times cited 8 Open Access
Notes Approved Most recent IF: 3.411; 2002 IF: 4.207
Call Number (down) UA @ lucian @ c:irua:94932 Serial 2775
Permanent link to this record
 
 
Author Baelus, B.J.; Yampolskii, S.V.; Peeters, F.M.
Title Magnetic coupling between mesoscopic superconducting rings Type A1 Journal article
Year 2002 Publication Physica: C : superconductivity Abbreviated Journal Physica C
Volume 369 Issue 1/4 Pages 366-369
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract Using the nonlinear Ginzburg-Landau theory we investigated the dependence of the magnetic coupling between two concentric mesoscopic superconducting rings on their thickness. The size of this magnetic coupling increases with the thickness of the rings. (C) 2001 Elsevier Science B.V. All rights reserved.
Address
Corporate Author Thesis
Publisher Place of Publication Amsterdam Editor
Language Wos 000174200000067 Publication Date 2002-07-25
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0921-4534; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 1.404 Times cited 1 Open Access
Notes Approved Most recent IF: 1.404; 2002 IF: 0.912
Call Number (down) UA @ lucian @ c:irua:94931 Serial 1865
Permanent link to this record
 
 
Author Yampolskii, S.V.; Peeters, F.M.
Title Giant vortices in small mesoscopic disks : an approximate description Type A1 Journal article
Year 2002 Publication Physica: C : superconductivity Abbreviated Journal Physica C
Volume 369 Issue 1/4 Pages 347-350
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract We present an approximate description of the giant vortex state in a thin mesoscopic superconducting disk within the phenomenological Ginzburg-Landau approach. Analytical asymptotic expressions for the energies of the states with fixed vorticity are obtained when a small magnetic flux is accumulated in the disk. The spectrum of the lowest Landau levels of such a disk is also discussed. (C) 2001 Elsevier Science B.V. All rights reserved.
Address
Corporate Author Thesis
Publisher Place of Publication Amsterdam Editor
Language Wos 000174200000063 Publication Date 2002-07-25
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0921-4534; ISBN Additional Links UA library record; WoS full record
Impact Factor 1.404 Times cited Open Access
Notes Approved Most recent IF: 1.404; 2002 IF: 0.912
Call Number (down) UA @ lucian @ c:irua:94930 Serial 1342
Permanent link to this record
 
 
Author Morozov, V.A.; Belik, A.A.; Stefanovich, S.Y.; Grebenev, V.V.; Lebedev, O.I.; Van Tendeloo, G.; Lazoryak, B.I.
Title High-temperature phase transition in the whitlockite-type phosphate Ca9In(PO4)7 Type A1 Journal article
Year 2002 Publication Journal of solid state chemistry Abbreviated Journal J Solid State Chem
Volume 165 Issue 2 Pages 278-288
Keywords A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract The double phosphate Ca9In(PO4)(7) was obtained by solid-state reaction and was studied by room and high-temperature Xray powder diffraction, electron diffraction, high-resolution electron microscopy, second-harmonic generation (SHG) technique, differential scanning calorimetry, dielectric and conductivity measurements. The beta-Ca9In(PO4)(7) room-temperature phase is related to the mineral whitlockite and is similar to beta-Ca-3(PO4)(2). It has space group R (3) over barc, with unit cell parameters: a = 10.4008(1) Angstrom, c = 37.272(1) Angstrom, Z = 6. The structure was refined by the Rietveld method (R-wp = 4.69, R-I = 1.81). A reversible first-order beta <----> beta' phase transition of the ferroelectric type with T-c = 902 K is revealed by SHG, differential scanning calorimetry and dielectric measurements. The centrosymmetric beta'-Ca9In(PO4)(7) (973 K) has space group R (3) over barc, a = 10.4611(2) Angstrom, c = 37.874 (1) Angstrom (R-wp = 4.27, R-I = 4.11). Compared to the low-temperature beta-Ca9In(PO4)(7) structure, beta'-Ca9In(PO4)(7) can be described as an orientational disordering of the P1O(4) tetrahedra together with a calcium disordering on the M3 site. (C) 2002 Elsevier Science (USA).
Address
Corporate Author Thesis
Publisher Place of Publication London Editor
Language Wos 000175916000010 Publication Date 2002-10-06
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0022-4596; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 2.299 Times cited 57 Open Access
Notes Approved Most recent IF: 2.299; 2002 IF: 1.671
Call Number (down) UA @ lucian @ c:irua:94926 Serial 1467
Permanent link to this record
 
 
Author Badalyan, S.M.; Peeters, F.M.
Title Joule heat in a two-dimensional electron gas exposed to a normal non-homogeneous magnetic field of a 'chess' configuration Type A1 Journal article
Year 2002 Publication Physica: B : condensed matter Abbreviated Journal Physica B
Volume 316 Issue Pages 216-218
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract We have calculated analytically the spatial distribution of the electric field and current density, and obtained the Joule heat generation rate in a two-dimensional electron gas (2DEG) subjected to a non-homogeneous magnetic field of a 'chess' configuration. The generation of the Joule heat from the 2DEG is mainly concentrated near the singular corners of each 'chess' field and tends to zero in other corners. (C) 2002 Elsevier Science B.V. All rights reserved.
Address
Corporate Author Thesis
Publisher Place of Publication Amsterdam Editor
Language Wos 000176297400047 Publication Date 2002-10-15
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0921-4526; ISBN Additional Links UA library record; WoS full record
Impact Factor 1.386 Times cited Open Access
Notes Approved Most recent IF: 1.386; 2002 IF: 0.609
Call Number (down) UA @ lucian @ c:irua:94925 Serial 1753
Permanent link to this record
 
 
Author Freire, J.A.K.; Freire, V.N.; Farias, G.A.; Peeters, F.M.
Title Exciton trapping in a periodically modulated magnetic field Type A1 Journal article
Year 2002 Publication Brazilian journal of physics Abbreviated Journal Braz J Phys
Volume 32 Issue 2 Pages 310-313
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract The behavior of excitons in spatially modulated magnetic fields is described taking into account the exciton spin contribution. The results show that the exciton trapping in periodic magnetic fields is possible and dependent on the modulation profile.
Address
Corporate Author Thesis
Publisher Place of Publication São Paulo Editor
Language Wos 000176522000016 Publication Date 2005-04-18
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0103-9733; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 0.732 Times cited 1 Open Access
Notes Approved Most recent IF: 0.732; 2002 IF: 0.678
Call Number (down) UA @ lucian @ c:irua:94923 Serial 1120
Permanent link to this record
 
 
Author Baelus, B.J.; Yampolskii, S.V.; Peeters, F.M.
Title Coupled mesoscopic superconductors : Ginzburg-Landau theory Type A1 Journal article
Year 2002 Publication Physical review : B : condensed matter and materials physics Abbreviated Journal Phys Rev B
Volume 66 Issue 2 Pages 024517-024517,14
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract The magnetic coupling between two concentric mesoscopic superconductors with nonzero thickness is studied using the nonlinear Ginzburg-Landau theory. We calculated the free energy, the expelled field, the total field profile, the Cooper-pair density, and the current density distribution. By putting a smaller superconducting disk or ring in the center of a larger ring, the properties change drastically. Extra ground-state transitions are found, where the total vorticity stays the same, but the vorticity of the inner superconductor changes by 1. Due to the magnetic coupling, the current in the external ring exhibits extra jumps at the transition fields where the vorticity of the inner superconductor changes. In this case, for certain temperatures, re-entrant behavior and switching on and off of the superconducting behavior of the rings are found as a function of the magnetic field. A H-T phase diagram is obtained for the situation where the inner ring has a higher critical temperature than the outer ring. An analytic expression for the magnetic coupling is obtained for thin rings and extreme type-II superconductors.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 000177338400112 Publication Date 2002-10-01
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0163-1829;1095-3795; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 3.836 Times cited 11 Open Access
Notes Approved Most recent IF: 3.836; 2002 IF: NA
Call Number (down) UA @ lucian @ c:irua:94920 Serial 536
Permanent link to this record
 
 
Author Shi, J.; Peeters, F.M.; Edmonds, K.W.; Gallagher, B.L.
Title Even-odd transition in the Shubnikov-de Haas oscillations in a two-dimensional electron gas subjected to periodic magnetic and electric modulations Type A1 Journal article
Year 2002 Publication Physical review : B : condensed matter and materials physics Abbreviated Journal Phys Rev B
Volume 66 Issue 3 Pages 035328-035328,9
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract We investigate low-temperature magnetotransport of high-mobility two-dimensional electron gases subjected to one-dimensional periodic magnetic and electric modulations. Our previous quantum perturbation theory is extended to lower temperatures and the energy broadening due to impurity scattering is incorporated. Numerical calculations are made for situations where several Landau bands overlap. We find that the Shubnikov-de Haas (SdH) oscillations are dominated by collisional resistance. The amplitudes of the SdH oscillations are strongly modulated and the positions of the SdH minima switch between even and odd Landau-level filling factors, in the resistance both parallel and perpendicular to the one-dimensional modulation. This is a consequence of the internal structure (i.e., smeared out van Hove singularities) of overlapping Landau bands. Our theoretical results are in good agreement with recent experiments.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 000177338500090 Publication Date 2002-10-01
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0163-1829;1095-3795; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 3.836 Times cited 32 Open Access
Notes Approved Most recent IF: 3.836; 2002 IF: NA
Call Number (down) UA @ lucian @ c:irua:94918 Serial 1091
Permanent link to this record
 
 
Author Vodolazov, D.I.; Peeters, F.M.
Title Dynamic transitions between metastable states in a superconducting ring Type A1 Journal article
Year 2002 Publication Physical review : B : condensed matter and materials physics Abbreviated Journal Phys Rev B
Volume 66 Issue 5 Pages 054537-054537,7
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract Applying the time-dependent Ginzburg-Landau equations, transitions between metastable states of a superconducting ring are investigated in the presence of an external magnetic field. It is shown that if the ring exhibits several metastable states at a particular magnetic field, the transition from one metastable state to another one is governed by both the relaxation time of the absolute value of the order parameter tau(\psi\) and the relaxation time of the phase of the order parameter tau(phi). We found that the larger the ratio tau(\psi\)/tau(phi), the closer the final state will be to the absolute minimum of the free energy, i.e., the thermodynamic equilibrium. The transition to the final state occurs through a subsequent set of single phase slips at a particular point along the ring.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 000177873000143 Publication Date 2002-08-30
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0163-1829;1095-3795; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 3.836 Times cited 34 Open Access
Notes Approved Most recent IF: 3.836; 2002 IF: NA
Call Number (down) UA @ lucian @ c:irua:94917 Serial 768
Permanent link to this record
 
 
Author Verberck, B.; Nikolaev, A.V.; Michel, K.H.
Title Theoretical model for the structural phase transition at the metal-insulator transition in polymerized KC60 Type A1 Journal article
Year 2002 Publication Physical Review B Abbreviated Journal Phys Rev B
Volume 66 Issue 16 Pages 165425-165425,14
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract The recently discovered structural transition in polymerized KC60 at about 50 K results in a doubling of the unit cell volume and accompanies the metal-insulator transition. Here we show that the ((a) over right arrow+(c) over right arrow,(b) over right arrow,(a) over right arrow-(c) over right arrow) superstructure results from small orientational charge density waves along the polymer chains and concomitant displacements of the surrounding K+ ions. The effect is specific for the space group Pmnn of KC60 and is absent in RbC60 and CsC60 (space group I2/m). The mechanism is relevant for the metal-insulator transition.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 000179286400135 Publication Date 2002-10-30
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0163-1829;1095-3795; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 3.836 Times cited 10 Open Access
Notes Approved Most recent IF: 3.836; 2002 IF: NA
Call Number (down) UA @ lucian @ c:irua:94907 Serial 3608
Permanent link to this record
 
 
Author Helm, M.; Peeters, F.M.; DeRosa, F.; Colas, E.; Harbison, J.P.; Florez, L.T.
Title Far-infrared spectroscopy of minibands and confined donors in GaAs/AlxGa1-xAs superlattices Type A1 Journal article
Year 1991 Publication Physical review : B : condensed matter and materials physics Abbreviated Journal Phys Rev B
Volume 43 Issue Pages 13983-13991
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract
Address
Corporate Author Thesis
Publisher Place of Publication Lancaster, Pa Editor
Language Wos A1991FQ97400019 Publication Date 0000-00-00
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1098-0121; 0163-1829 ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 3.736 Times cited 77 Open Access
Notes Approved no
Call Number (down) UA @ lucian @ c:irua:949 Serial 1174
Permanent link to this record
 
 
Author Ivanov, V.A.; Betouras, J.J.; Peeters, F.M.
Title MgB2 : superconductivity and pressure effects Type P1 Proceeding
Year 2003 Publication Abbreviated Journal
Volume Issue Pages 35-46
Keywords P1 Proceeding; Condensed Matter Theory (CMT)
Abstract We present a Ginzburg-Landau theory for a two-band superconductor with emphasis on MgB2. We propose experiments which lead to identification of the possible scenarios: whether both sigma- and pi-bands superconduct or sigma-alone. According to the second scenario a microscopic theory of superconducting MgB2 is proposed based on the strongly interacting or-electrons and non-correlated pi-electrons of boron ions. The kinematic and Coulomb interactions of sigma-electrons provide the superconducting state with an anisotropic gap of s(*)-wave symmetry. The critical temperature T-c has a non-monotonic dependence on the distance r between the centers of gravity of sigma- and pi-bands. The position of MgB2 on a bell-shaped curve T-c (r) is identified in the overdoped region. The derived superconducting density of electronic states is in agreement with available experimental and theoretical data. It is argued that the effects of pressure are crucial to identify the microscopic origin of superconductivity in MgB2. Possibilities for increase of T, are discussed.
Address
Corporate Author Thesis
Publisher Springer Place of Publication Dordrecht Editor
Language Wos Publication Date 0000-00-00
Series Editor Series Title Abbreviated Series Title
Series Volume 106 Series Issue Edition
ISSN 1-4020-1372-8 ISBN Additional Links UA library record; WoS full record;
Impact Factor Times cited Open Access
Notes Approved Most recent IF: NA
Call Number (down) UA @ lucian @ c:irua:94869 Serial 2020
Permanent link to this record
 
 
Author Yandouzi, M.; Pauwels, B.; Schryvers, D.; Van Swygenhoven, H.; Van Tendeloo, G.
Title Structural characterization of nanostructured Ni3Al processed by inert gas condensation Type A1 Journal article
Year 2003 Publication Diffusion and defect data : solid state data : part A : defect and diffusion forum Abbreviated Journal
Volume 213 Issue 2 Pages 19-30
Keywords A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract High-resolution transmission electron microscopy was performed on compacted Ni(3)Al nanostructured material prepared by the inert gas condensation technique. From electron diffraction data an incomplete L1(2) ordering of the crystallites is observed in the free particles as well as in the room temperature compacted samples. However, a completely ordered L1(2) structure with much bigger and well-defined crystallites exhibiting several defects is observed in material compacted and annealed at 773 K. Sharp crystallite boundaries as well as amorphous material and voids are observed in between crystallites in all samples, the former being dominant in the annealed material, the latter in the as-prepared one.
Address
Corporate Author Thesis
Publisher Place of Publication Aedermannsdorf Editor
Language Wos Publication Date 0000-00-00
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1012-0386 ISBN Additional Links UA library record; WoS full record;
Impact Factor Times cited Open Access
Notes Approved Most recent IF: NA
Call Number (down) UA @ lucian @ c:irua:94868 Serial 3221
Permanent link to this record
 
 
Author Horvath, Z.E.; Biro, L.P.; Van Tendeloo, G.; Tondeur, C.; Bister, G.; Pierard, N.; Fonseca, A.; Nagy, J.B.
Title Optimization of the amount of catalyst and reaction time in single wall nanotube production Type A1 Journal article
Year 2003 Publication Diffusion and defect data : solid state data : part B : solid state phenomena Abbreviated Journal Solid State Phenom
Volume 94 Issue Pages 271-274
Keywords A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract The influence of the amount of catalyst and the reaction time on the quantity and quality of catalytically grown single wall carbon nanotubes (SWNT) was investigated. The aim was to optimize some of the SWNT growth parameters using TEM and HRTEM. The thickness of catalyst layer influences the synthesis of the nanotube because the gas composition can differ between top and bottom. Microscopic investigation of the grown SWNT samples showed that the thicker the catalyst layer the lower relative nanotube content, so the deeper parts of the catalyst layer are less effective: The optimum time for the reaction was found to be 10 minutes. This may be understood assuming that nanotube growth needs an initial incubation time while the activity of the catalyst decreases steadily until the nariotube growth stops.
Address
Corporate Author Thesis
Publisher Place of Publication Vaduz Editor
Language Wos Publication Date 0000-00-00
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1012-0394; 1662-9779 ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor Times cited Open Access
Notes Approved Most recent IF: NA
Call Number (down) UA @ lucian @ c:irua:94860 Serial 2490
Permanent link to this record
 
 
Author Betouras, J.J.; Ivanov, V.A.; Peeters, F.M.
Title Ginzburg-Landau theory and effects of pressure on a two-band superconductor : application to MgB2 Type A1 Journal article
Year 2003 Publication European physical journal : B : condensed matter and complex systems Abbreviated Journal Eur Phys J B
Volume 31 Issue 3 Pages 349-354
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract We present a model of pressure effects of a two-band superconductor based on a Ginzburg-Landau free energy with two order parameters. The parameters of the theory are pressure as well as temperature dependent. New pressure effects emerge as a result of the competition between the two bands. The theory then is applied to MgB2. We identify two possible scenaria regarding the fate of the two Q subbands under pressure, depending on whether or not both subbands are above the Fermi energy at ambient pressure. The splitting of the two subbands is probably caused by the E-2g, distortion. If only one subband is above the Fermi energy at ambient pressure (scenario I), application of pressure diminishes the splitting and it is possible that the lower subband participates in the superconductivity. The corresponding crossover pressure and Gruneisen parameter are estimated. In the second scenario both bands start above the Fermi energy and they move below it, either by pressure or via the substitution of Mg by Al. In both scenaria, the possibility of electronical topological transition is emphasized. Experimental signatures of both scenaria are presented and existing experiments are discussed in the light of the different physical pictures.
Address
Corporate Author Thesis
Publisher Place of Publication Berlin Editor
Language Wos 000181614300008 Publication Date 2004-03-20
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1434-6028;1434-6036; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 1.461 Times cited 10 Open Access
Notes Approved Most recent IF: 1.461; 2003 IF: 1.457
Call Number (down) UA @ lucian @ c:irua:94859 Serial 1343
Permanent link to this record
 
 
Author Nikolaev, A.V.; Michel, K.H.
Title Symmetry lowering at the structural phase transitions in NpO2 and UO2 Type A1 Journal article
Year 2003 Publication Physical review : B : condensed matter and materials physics Abbreviated Journal Phys Rev B
Volume 68 Issue 5 Pages 054112-054112,7
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract The structural phase transitions with electric-quadrupole long-range order in NpO2 (Fm (3) over barm-->Pn (3) over barm) and UO2 (Fm (3) over barm-->Pa (3) over bar) are analyzed from a group theoretical point of view. In both cases, the symmetry lowering involves three quadrupolar components belonging to the irreducible representation T-2g (Gamma(5)) of O-h and condensing in a triple-q structure at the X point of the Brillouin zone. The Pa (3) over bar structure is close to Pn (3) over barm, but allows for oxygen displacements. The Pa (3) over bar ordering leads to an effective electrostatic attraction between electronic quadrupoles while the Pn (3) over barm ordering results in a repulsion between them. It is concluded that the Pn (3) over barm structure can be stabilized only through some additional process such as strengthening of the chemical bonding between Np and O. We also derive the relevant structure-factor amplitudes for Pn (3) over barm and Pa (3) over bar, and the effect of domains on resonant x-ray scattering experiments.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 000185240100038 Publication Date 2003-08-29
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0163-1829;1095-3795; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 3.836 Times cited 15 Open Access
Notes Approved Most recent IF: 3.836; 2003 IF: NA
Call Number (down) UA @ lucian @ c:irua:94847 Serial 3405
Permanent link to this record
 
 
Author Abakumov, A.M.; Alekseeva, A.M.; Rozova, M.G.; Antipov, E.V.; Lebedev, O.I.; Van Tendeloo, G.
Title Ordering of tetrahedral chains in the Sr2MnGaO5 brownmillerite Type A1 Journal article
Year 2003 Publication Journal of solid state chemistry Abbreviated Journal J Solid State Chem
Volume 174 Issue 2 Pages 319-328
Keywords A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract Tetrahedral chain ordering in the Sr2MnGaO5 structure is studied using electron diffraction (ED) and high-resolution electron microscopy. The ED patterns show the presence of satellite reflections, which indicate a commensurately modulated structure with a = 5.4056(8) Angstrom b 16.171(3) Angstrom, c = 5.5592(7) Angstrom, q – 1/2c*, superspace group Immma(00gamma,)s00. The Superstructure arises due to ordering of the two types of symmetry related tetrahedral chains (L and R) according to a ... LRLR ... sequence, where L and R chains alternate along the c-axis within the same (GaO) layer. Numerous defects at different structural levels were observed, comprising interleaving L and R chains, violation of the ... LRLR ... chain sequence within one layer, different stacking modes of the ... LRLR ... ordered layers with subsequent alternation of blocks of different width along the h-axis of the brownmillerite subcell and island fragmentation of the modulated superstructure. By in situ heating ED experiments it is found that the long-range ordering of the tetrahedral chains is stable tip to 665degreesC and is completely suppressed at 905degreesC. (C) 2003 Elsevier Inc. All rights reserved.
Address
Corporate Author Thesis
Publisher Place of Publication London Editor
Language Wos 000185180500011 Publication Date 2003-07-22
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0022-4596; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 2.299 Times cited 34 Open Access
Notes Approved Most recent IF: 2.299; 2003 IF: 1.413
Call Number (down) UA @ lucian @ c:irua:94846 Serial 2506
Permanent link to this record
 
 
Author Chen, Z.; Feng, X.; Xu, Y.; Yu, M.Y.
Title Optical bistability and multistability in four-level systems Type A1 Journal article
Year 2003 Publication Physica scripta Abbreviated Journal Phys Scripta
Volume 68 Issue 3 Pages 199-204
Keywords A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Abstract The optical behavior of a four-level system in a ring cavity driven by two coherent laser fields is studied. One laser field is treated as the incident field and the other the control field, respectively. It is found that there is optical transparency when the difference between the two frequency detunings of the incident and control fields from the corresponding atomic transition frequencies is zero. Optical bistability can be produced and controlled by increasing the magnitude of the frequency difference. The bistable hysteresis becomes larger when the frequency difference is increased. Further increase of the latter can lead to onset of multistability.
Address
Corporate Author Thesis
Publisher Place of Publication Stockholm Editor
Language Wos 000185204400005 Publication Date 2003-08-04
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0031-8949;1402-4896; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 1.28 Times cited 8 Open Access
Notes Approved Most recent IF: 1.28; 2003 IF: 0.688
Call Number (down) UA @ lucian @ c:irua:94844 Serial 2471
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Author Verberck, B.; Nikolaev, A.V.; Michel, K.H.
Title Orientational charge density waves and the metal-insulator transition in polymerized KC60 Type A1 Journal article
Year 2004 Publication AIP conference proceedings Abbreviated Journal
Volume 723 Issue Pages 339-342
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract Polymerized KC60 undergoes a structural phase transition accompanied by a metal-insulator transition around 50 K. To explain the structural aspect, a mechanism involving small orientational deviations of the valence electron density on every C-60 monomer orientational charge density waves (OCDWs) – has already been proposed earlier. In the present work, we address the metal-insulator transition using the OCDW concept. We are inspired by the analogy between a polymer chain exhibiting an OCDW and a linear atomic chain undergoing a static lattice deformation doubling the unit cell: such a deformation implies a band gap at the zone boundary, yielding an insulating state (Peierls instability). Within our view, a similar mechanism occurs in polymerized KC60; the OCDW plays the role of the lattice deformation. We present tight-binding band structure calculations and conclude that the metal-insulator transition can indeed be explained using OCDWs, but that the threedimensionality of the crystal plays an unexpected key role.
Address
Corporate Author Thesis
Publisher Place of Publication New York Editor
Language Wos Publication Date 0000-00-00
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0094-243x ISBN Additional Links UA library record; WoS full record;
Impact Factor Times cited Open Access
Notes Approved Most recent IF: NA
Call Number (down) UA @ lucian @ c:irua:94831 Serial 2513
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Author Musolino, N.; Bals, S.; Van Tendeloo, G.; Clayton, N.; Walker, E.; Flukiger, R.
Title Investigation of (Bi,Pb)2212 crystals : observation of modulation-free phase Type A1 Journal article
Year 2004 Publication Physica: C : superconductivity Abbreviated Journal Physica C
Volume 401 Issue 1-4 Pages 270-272
Keywords A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract We report the complete disappearance of the structural modulation in heavily lead-doped Bi2-xPbxSr2CaCu2O8+delta crystals observed by transmission electron microscopy. Crystals with a nominal lead content of x = 0.8, corresponding to an effective lead content of x = 0.39, yield the non-modulated phase. The superconducting properties of this modulation-free phase (beta phase) have been studied and compared to those of undoped crystals displaying the modulated phase (alpha phase). Magnetisation measurements reveal that the irreversibility field H-irr(T) and relaxation rates are strongly improved within the beta phase. Measurements of the lower critical field, H-cl, show that the anisotropy factor, E, is considerably reduced in the modulation-free crystals. This is the signature of stronger coupling between CuO2 layers which in turn deeply influences the effectiveness of the pinning. These measurements explain the enhanced pinning properties in moderately Pb-doped crystals in which the a phase and P phase coexist. The enhanced pinning is not only due to the alpha/beta interfaces, which act as effective pinning centers: the emergence of modulation-free domains, characterized by a strongly reduced anisotropy, also significantly contribute to this effect. (C) 2003 Elsevier B.V. All rights reserved.
Address
Corporate Author Thesis
Publisher Place of Publication Amsterdam Editor
Language Wos 000187852100050 Publication Date 2003-10-17
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0921-4534; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 1.404 Times cited 9 Open Access
Notes Approved Most recent IF: 1.404; 2004 IF: 1.072
Call Number (down) UA @ lucian @ c:irua:94809 Serial 1730
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Author Xu, Y.; Jia, D.-J.; Chen, Z.; Gao, Y.; Li, F.-S.
Title The mode-deviation effect of trapped spinor bose gas beyond mean field theory Type A1 Journal article
Year 2004 Publication International journal of modern physics: B: condensed matter physics, statistical physics, applied physics Abbreviated Journal Int J Mod Phys B
Volume 18 Issue 9 Pages 1339-1349
Keywords A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Abstract The deviation effect of spinor mode from the single-mode for a spin-1 Bose gas of trapped atoms is studied beyond the mean field theory. Based on the effective Hamiltonian with nondegenerated level of the collective spin states, the splitting level of the system energy due to the deviation effect has been calculated. For the large condensates of (87)Rb and (23)Na with atom number N > 10(5), the splitting fraction of the energy, arising from the magnetization exhibited by the trapped Bose gas, is found to have a typical order of (10(-4) similar to 10(-8)), decreasing as N(-2) for (87)Rb and increasing as -N(-2) for 23 Na, respectively.
Address
Corporate Author Thesis
Publisher Place of Publication Singapore Editor
Language Wos 000222342400008 Publication Date 2004-06-18
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0217-9792;1793-6578; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 0.736 Times cited 1 Open Access
Notes Approved Most recent IF: 0.736; 2004 IF: 0.361
Call Number (down) UA @ lucian @ c:irua:94805 Serial 2096
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Author Xu, W.; Peeters, F.M.; Devreese, J.T.
Title The hot electron distribution of two-dimensional electrons in a polar semiconductor at zero temperature Type A3 Journal article
Year 1991 Publication Journal of physics: C: condensed matter Abbreviated Journal
Volume 3 Issue Pages 1783-1791
Keywords A3 Journal article; Condensed Matter Theory (CMT); Theory of quantum systems and complex systems
Abstract
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos A1991FE35700009 Publication Date 0000-00-00
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor Times cited 1 Open Access
Notes Approved no
Call Number (down) UA @ lucian @ c:irua:948 Serial 1490
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Author Molnar, B.; Vasilopoulos, P.; Peeters, F.M.
Title Spin-dependent transmission through a chain of rings : influence of a periodically modulated spin-orbit interaction strength or ring radius Type A1 Journal article
Year 2004 Publication Applied physics letters Abbreviated Journal Appl Phys Lett
Volume 85 Issue 4 Pages 612-614
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract We study ballistic electron transport through a finite chain of quantum circular rings in the presence of spin-orbit interaction of strength alpha. For a single ring, the transmission and reflection coefficients are obtained analytically and from them the conductance for a chain of rings as a function of alpha and of the wave vector k of the incident electron. We show that due to destructive spin interferences, the chain can be totally opaque for certain ranges of k, the width of which depends on the value of alpha. A periodic modulation of the strength alpha or of the ring radius widens the gaps considerably and produces a nearly binary conductance output. (C) 2004 American Institute of Physics.
Address
Corporate Author Thesis
Publisher American Institute of Physics Place of Publication New York, N.Y. Editor
Language Wos 000222855400034 Publication Date 2004-07-23
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0003-6951; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 3.411 Times cited 26 Open Access
Notes Approved Most recent IF: 3.411; 2004 IF: 4.308
Call Number (down) UA @ lucian @ c:irua:94799 Serial 3085
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Author Duan, Z.L.; Chen, Z.Y.; Zhang, J.T.; Feng, X.L.; Xu, Z.Z.
Title Scheme for the generation of entangled atomic state in cavity QED Type A1 Journal article
Year 2004 Publication European physical journal : D : atomic, molecular and optical physics Abbreviated Journal Eur Phys J D
Volume 30 Issue 2 Pages 275-278
Keywords A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Abstract We propose a scheme to generate the entangled state of two Lambda-type three-level atoms trapped in a cavity. The atoms are initially prepared in their excited state and the cavity in vacuum state. Each atom has two possibilities to deexcite to one of the ground states. If two different polarized photons are detected subsequently, it is sure that both atoms are in different ground states. But which atom is in which ground state cannot be determined, the atoms are thus prepared in a superposition of two ground states, i.e., an entangled state. In comparison with the proposal of Hong and Lee [Phys. Rev. Lett. 89, 237901 (2002)], the requirement of a single polarized photon source can be avoided in our scheme.
Address
Corporate Author Thesis
Publisher Place of Publication Berlin Editor
Language Wos 000223019400013 Publication Date 2004-07-05
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1434-6060;1434-6079; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 1.288 Times cited 4 Open Access
Notes Approved Most recent IF: 1.288; 2004 IF: 1.692
Call Number (down) UA @ lucian @ c:irua:94796 Serial 2954
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Author Vasilopoulos, P.; Molnar, B.; Peeters, F.M.
Title Magnetoconductance through a chain of rings in the presence of spin-orbit interaction Type A1 Journal article
Year 2004 Publication International journal of modern physics: B: condensed matter physics, statistical physics, applied physics Abbreviated Journal Int J Mod Phys B
Volume 18 Issue 27-29 Pages 3661-3664
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract Ballistic electron transport through a finite chain of quantum circular rings is studied in the presence of the Rashba coupling, of strength a, and of a perpendicular magnetic field B. The transmission and reflection coefficients for a single ring, obtained analytically, help obtain the conductance through a chain of rings as a function of the strength a, the field B, and of the wave vector k of the incident electron. Due to destructive spin interferences caused by the Rashba coupling the chain can be totally opaque for certain ranges of k the width of which depends on values of a and B. Outside these ranges the conductance oscillates with high values between e(2)/h and 2e(2)/h. The effect of a periodic modulation of a or B on the conductance gaps is investigated. A periodic, square-wave conductance pattern, pertinent to the development of the spin transistor, results within wide stripes in the parameter space spanned by k, a, and B. Finite temperatures smoothen the square-wave profile of the conductance but do not alter its periodic character.
Address
Corporate Author Thesis
Publisher Place of Publication Singapore Editor
Language Wos 000227140200042 Publication Date 2005-04-12
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0217-9792;1793-6578; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 0.736 Times cited 2 Open Access
Notes Approved Most recent IF: 0.736; 2004 IF: 0.361
Call Number (down) UA @ lucian @ c:irua:94787 Serial 1914
Permanent link to this record
 
 
Author Mattauch, S.; Heger, G.; Michel, K.H.
Title High resolution neutron and X-ray diffraction studies as a function of temperature and electric field of the ferroelectric phase transition of RDP Type A1 Journal article
Year 2004 Publication Crystal research and technology Abbreviated Journal Cryst Res Technol
Volume 39 Issue 12 Pages 1027-1054
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract Neutron and high resolution X-ray diffraction investigations on perfect single crystals of RbH2PO4 (RDP), a hydrogen bonded ferroelectric of KDP type are reported. The results of crystal structure analysis from diffraction data, below and above the paraelectric – ferroelectric phase transition, support a disorder – order character Of [PO4H2](-)-groups. The tetragonal symmetry of the paraelectric phase with the double well potential of the hydrogen atoms obtained by diffraction, results simply from a time-space average of orthorhombic symmetry. According to the group – subgroup relation between the tetragonal space group 142d and the orthorhombic Fdd2 a short range order of ferroelectric clusters in the tetragonal phase is observed. With decreasing temperature the ferroelectric clusters increase and the long range interaction between their local polarisation vectors leads to the formation of lamellar ferroelectric domains with alternating polarisation directions at T-C = 147 K. From the high resolution X-ray data it is concluded that below T-C the ferroelastic strain in the (a,b)-plane leads to micro-angle grain boundaries at the domain walls. The tilt angle is enhanced by an applied electric field parallel to the ferroelectric axis. The resulting dislocations at the domain walls persist in the paraelectric phase leading to a memory effect for the arrangement of twin lamellae. With increased electric field the phase transition temperature T-C is decreased.
Address
Corporate Author Thesis
Publisher Place of Publication Berlin Editor
Language Wos 000225681100001 Publication Date 2004-11-12
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0232-1300;1521-4079; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 1 Times cited 12 Open Access
Notes Approved Most recent IF: 1; 2004 IF: 0.770
Call Number (down) UA @ lucian @ c:irua:94785 Serial 1459
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Author van Daele, B.; Van Tendeloo, G.; Ruythooren, W.; Derluyn, J.; Leys, M.R.; Germain, M.
Title Transmission electron microscopy characterisation of Ti and Al/Ti contacts on GaN and AlGaN/GaN Type A1 Journal article
Year 2005 Publication Springer proceedings in physics Abbreviated Journal
Volume 107 Issue Pages 389-392
Keywords A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract Transmission electron microscopy has been applied to study Ti and Al/Ti contacts on GaN and AlGaN/GaN as a function of annealing temperature. This has lead to a profound understanding of the role of Al, both in the contact formation on n-GaN and on AlGaN/GaN. Al in the AlGaN decreases the N-extraction by Ti out of the nitride, because of the strong Al-N bond. Al in the metal bilayer also reduces the N-extraction by Ti due to a preferential alloy mixing.
Address
Corporate Author Thesis
Publisher Place of Publication Berlin Editor
Language Wos Publication Date 0000-00-00
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0930-8989 ISBN Additional Links UA library record; WoS full record;
Impact Factor Times cited Open Access
Notes Approved Most recent IF: NA
Call Number (down) UA @ lucian @ c:irua:94775 Serial 3707
Permanent link to this record
 
 
Author Molnar, B.; Vasilopoulos, P.; Peeters, F.M.
Title Square-wave conductance through a chain of rings due to spin-orbit interaction Type P1 Proceeding
Year 2005 Publication AIP conference proceedings Abbreviated Journal
Volume 772 Issue Pages 1335-1336
Keywords P1 Proceeding; Condensed Matter Theory (CMT)
Abstract We study ballistic electron transport through a finite chain of quantum circular rings in the presence of spin-orbit interaction (SOI) of strength alpha. The transmission and reflection coefficients for a single ring, obtained analytical lylead to the conductance for a chain of rings as a function of alpha and of the wave vector k of the incident electron. Due to destructive spin interferences the chain can be totaly opaque for certain ranges of k the width of which depends on the value of alpha. A periodic modulation of a widens up the gaps considerably and produces a nearly binary conductance output.
Address
Corporate Author Thesis
Publisher Place of Publication New York Editor
Language Wos Publication Date 0000-00-00
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0094-243x ISBN Additional Links UA library record; WoS full record;
Impact Factor Times cited Open Access
Notes Approved Most recent IF: NA
Call Number (down) UA @ lucian @ c:irua:94771 Serial 3113
Permanent link to this record