Title
Ginzburg-Landau theory and effects of pressure on a two-band superconductor : application to <tex>$MgB_{2}$</tex> Ginzburg-Landau theory and effects of pressure on a two-band superconductor : application to <tex>$MgB_{2}$</tex>
Author
Faculty/Department
Faculty of Sciences. Physics
Publication type
article
Publication
Berlin ,
Subject
Physics
Source (journal)
European physical journal : B : condensed matter and complex systems. - Berlin
Volume/pages
31(2003) :3 , p. 349-354
ISSN
1434-6028
ISI
000181614300008
Carrier
E
Target language
English (eng)
Full text (Publishers DOI)
Affiliation
University of Antwerp
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.
E-info
https://repository.uantwerpen.be/docman/iruaauth/a42ef2/b181953.pdf
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