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Author |
Chen, Z.; Feng, X.; Xu, Y.; Yu, M.Y. |
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Title |
Optical bistability and multistability in four-level systems |
Type |
A1 Journal article |
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Year |
2003 |
Publication |
Physica scripta |
Abbreviated Journal |
Phys Scripta |
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Volume |
68 |
Issue |
3 |
Pages |
199-204 |
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Keywords |
A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT) |
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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. |
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Publisher |
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Place of Publication |
Stockholm |
Editor |
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Wos |
000185204400005 |
Publication Date |
2003-08-04 |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
0031-8949;1402-4896; |
ISBN |
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Additional Links  |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
1.28 |
Times cited |
8 |
Open Access |
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Notes |
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Approved |
Most recent IF: 1.28; 2003 IF: 0.688 |
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Call Number |
UA @ lucian @ c:irua:94844 |
Serial |
2471 |
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Author |
Abakumov, A.M.; Alekseeva, A.M.; Rozova, M.G.; Antipov, E.V.; Lebedev, O.I.; Van Tendeloo, G. |
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Title |
Ordering of tetrahedral chains in the Sr2MnGaO5 brownmillerite |
Type |
A1 Journal article |
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Year |
2003 |
Publication |
Journal of solid state chemistry |
Abbreviated Journal |
J Solid State Chem |
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Volume |
174 |
Issue |
2 |
Pages |
319-328 |
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Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT) |
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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. |
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Place of Publication |
London |
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Wos |
000185180500011 |
Publication Date |
2003-07-22 |
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Series Editor |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
0022-4596; |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
2.299 |
Times cited |
34 |
Open Access |
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Notes |
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Approved |
Most recent IF: 2.299; 2003 IF: 1.413 |
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Call Number |
UA @ lucian @ c:irua:94846 |
Serial |
2506 |
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Author |
Nikolaev, A.V.; Michel, K.H. |
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Title |
Symmetry lowering at the structural phase transitions in NpO2 and UO2 |
Type |
A1 Journal article |
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Year |
2003 |
Publication |
Physical review : B : condensed matter and materials physics |
Abbreviated Journal |
Phys Rev B |
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Volume |
68 |
Issue |
5 |
Pages |
054112-054112,7 |
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Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
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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. |
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Wos |
000185240100038 |
Publication Date |
2003-08-29 |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
0163-1829;1095-3795; |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
3.836 |
Times cited |
15 |
Open Access |
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Notes |
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Approved |
Most recent IF: 3.836; 2003 IF: NA |
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Call Number |
UA @ lucian @ c:irua:94847 |
Serial |
3405 |
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Author |
Betouras, J.J.; Ivanov, V.A.; Peeters, F.M. |
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Title |
Ginzburg-Landau theory and effects of pressure on a two-band superconductor : application to MgB2 |
Type |
A1 Journal article |
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Year |
2003 |
Publication |
European physical journal : B : condensed matter and complex systems |
Abbreviated Journal |
Eur Phys J B |
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Volume |
31 |
Issue |
3 |
Pages |
349-354 |
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Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
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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. |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
Berlin |
Editor |
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Language |
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Wos |
000181614300008 |
Publication Date |
2004-03-20 |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
1434-6028;1434-6036; |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
1.461 |
Times cited |
10 |
Open Access |
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Notes |
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Approved |
Most recent IF: 1.461; 2003 IF: 1.457 |
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Call Number |
UA @ lucian @ c:irua:94859 |
Serial |
1343 |
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