Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Vortex-matter in Multi-component Superconductors
KTH, School of Engineering Sciences (SCI), Theoretical Physics, Statistical Physics.
2012 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

The topic of this thesis is vortex-physics in multi component Ginzburg- Landau models. These models describe a newly discovered class of supercon- ductors with multiple superconducting gaps, and posses many properties that set them apart from single component models. The work presented here relies on large scale computer simulations using various numerical techniques, but also some analytical methods.

In Paper I, Type-1.5 Superconducting State from an Intrinsic Proximity Effect in Two-Band Superconductors, we show that in multiband supercon- ductors, even an extremely small interband proximity effect can lead to a qualitative change in the interaction potential between superconducting vor- tices by producing long-range intervortex attraction. This type of vortex interaction results in an unusual response to low magnetic fields, leading to phase separation into domains of two-component Meissner states and vortex droplets.

In paper II, Type-1.5 superconductivity in multiband systems: Effects of interband couplings, we investigate the appearance of Type-1.5 superconduc- tivity in the case with two active bands and substantial inter-band couplings. such as intrinsic Josephson coupling, mixed gradient coupling, and density- density interactions. We show that in the presence of these interactions, the system supports type-1.5 superconductivity with fundamental length scales being associated with the mass of the gauge field and two masses of normal modes represented by mixed combinations of the density fields.

In paper III, Semi-Meissner state and nonpairwise intervortex interactions in type-1.5 superconductors, we demonstrate the existence of nonpairwise in- teraction forces between vortices in multicomponent and layered supercon- ducting systems. Next, we consider the properties of vortex clusters in a semi-Meissner state of type-1.5 two-component superconductors. We show that under certain conditions nonpairwise forces can contribute to the forma- tion of very complex vortex states in type-1.5 regimes.

In paper IV, Length scales, collective modes, and type-1.5 regimes in three- band superconductors, we consider systems where frustration in phase differ- ences occur due to competing Josephson inter-band coupling terms. We show that gradients of densities and phase differences can be inextricably inter- twined in vortex excitations in three-band models. This can lead to very long-range attractive intervortex interactions and the appearance of type-1.5 regimes even when the intercomponent Josephson coupling is large. We also show that field-induced vortices can lead to a change of broken symmetry from U (1) to U (1) × Z2 in the system. In the type-1.5 regime, it results in a semi-Meissner state where the system has a macroscopic phase separation in domainswithbrokenU(1)andU(1)×Z2 symmetries.

In paper V, Topological Solitons in Three-Band Superconductors with Bro- ken Time Reversal Symmetry, we show that three-band superconductors with broken time reversal symmetry allow magnetic flux- carrying stable topolog- ical solitons. They can be induced by fluctuations or quenching the system through a phase transition. It can provide an experimental signature of the time reversal symmetry breakdown. 

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2012. , 74 p.
Series
Trita-FYS, ISSN 0280-316X
Keyword [en]
Superconductivity
National Category
Condensed Matter Physics
Identifiers
URN: urn:nbn:se:kth:diva-109787ISBN: 978-91-7501-611-5 (print)OAI: oai:DiVA.org:kth-109787DiVA: diva2:584315
Presentation
2013-01-14, FA32, Albanova universitetscentrum, Roslagstullsbacke 21, Stockholm, 10:00 (English)
Opponent
Supervisors
Note

QC 20130109

Available from: 2013-01-09 Created: 2013-01-08 Last updated: 2013-01-09Bibliographically approved
List of papers
1. Type-1.5 Superconducting State from an Intrinsic Proximity Effect in Two-Band Superconductors
Open this publication in new window or tab >>Type-1.5 Superconducting State from an Intrinsic Proximity Effect in Two-Band Superconductors
2010 (English)In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 105, no 6, 067003- p.Article in journal (Refereed) Published
Abstract [en]

We show that in multiband superconductors, even an extremely small interband proximity effect can lead to a qualitative change in the interaction potential between superconducting vortices by producing long-range intervortex attraction. This type of vortex interaction results in an unusual response to low magnetic fields leading to phase separation into domains of two-component Meissner states and vortex droplets.

Keyword
Interaction potentials, Interband, Low magnetic fields, Meissner state, Multiband superconductors, Proximity effects, Qualitative changes, Superconducting state, Superconducting vortices, Two-band superconductors, Two-component, Vortex interactions, Magnetic domains, Magnetic fields, Phase separation, Superconducting materials, Vortex flow
National Category
Physical Sciences
Identifiers
urn:nbn:se:kth:diva-29414 (URN)10.1103/PhysRevLett.105.067003 (DOI)000280612400010 ()2-s2.0-77955320910 (Scopus ID)
Funder
Swedish Research CouncilKnut and Alice Wallenberg Foundation
Note
QC 20110216Available from: 2011-02-16 Created: 2011-02-02 Last updated: 2017-12-11Bibliographically approved
2. Type-1.5 superconductivity in multiband systems: Effects of interband couplings
Open this publication in new window or tab >>Type-1.5 superconductivity in multiband systems: Effects of interband couplings
2011 (English)In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 83, no 17, 174509- p.Article in journal (Refereed) Published
Abstract [en]

In contrast to single-component superconductors, which are described at the level of Ginzburg-Landau theory by a single parameter kappa and are divided in type-I kappa < 1/root 2 and type-II kappa > 1/root 2 classes, two-component systems in general possess three fundamental length scales and have been shown to possess a separate "type-1.5" superconducting state. In that state, as a consequence of the extra fundamental length scale, vortices attract one another at long range but repel at shorter ranges, and therefore should form clusters in low magnetic fields. In this work we investigate the appearance of type-1.5 superconductivity and the interpretation of the fundamental length scales in the case of two active bands with substantial interband couplings such as intrinsic Josephson coupling, mixed gradient coupling, and density-density interactions. We show that in the presence of substantial intercomponent interactions of the above types the system supports type-1.5 superconductivity with fundamental length scales being associated with the mass of the gauge field and two masses of normal modes represented by mixed combinations of the density fields.

National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:kth:diva-34200 (URN)10.1103/PhysRevB.83.174509 (DOI)000290477200010 ()2-s2.0-79961122308 (Scopus ID)
Funder
Knut and Alice Wallenberg FoundationSwedish Research Council
Note
QC 20110610Available from: 2011-06-10 Created: 2011-05-30 Last updated: 2017-12-11Bibliographically approved
3. Semi-Meissner state and nonpairwise intervortex interactions in type-1.5 superconductors
Open this publication in new window or tab >>Semi-Meissner state and nonpairwise intervortex interactions in type-1.5 superconductors
2011 (English)In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 84, no 13, 134515- p.Article in journal (Refereed) Published
Abstract [en]

We demonstrate the existence of nonpairwise interaction forces between vortices in multicomponent and layered superconducting systems. That is, in contrast to most common models, the interaction in a group of such vortices is not a universal superposition of Coulomb or Yukawa forces. Next, we consider the properties of vortex clusters in a semi-Meissner state of type-1.5 two-component superconductors. We show that under certain conditions nonpairwise forces can contribute to the formation of very complex vortex states in type-1.5 regimes.

National Category
Physical Sciences
Identifiers
urn:nbn:se:kth:diva-45586 (URN)10.1103/PhysRevB.84.134515 (DOI)000295868900009 ()2-s2.0-80155143574 (Scopus ID)
Funder
Swedish Research CouncilKnut and Alice Wallenberg Foundation
Note
QC 20111107Available from: 2011-11-07 Created: 2011-10-31 Last updated: 2017-12-08Bibliographically approved
4. Length scales, collective modes, and type-1.5 regimes in three-band superconductors
Open this publication in new window or tab >>Length scales, collective modes, and type-1.5 regimes in three-band superconductors
2011 (English)In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 84, no 13, 134518- p.Article in journal (Refereed) Published
Abstract [en]

The recent discovery of iron pnictide superconductors has resulted in a rapidly growing interest in multiband models with more than two bands. In this work we specifically focus on the properties of three-band Ginzburg-Landau models which do not have direct counterparts in more studied two-band models. First we derive normal modes and characteristic length scales in the conventional U(1) three-band Ginzburg-Landau model as well as in its time-reversal symmetry-broken counterpart with U(1) x Z(2) symmetry. We show that, in the latter case, the normal modes are mixed phase-density collective excitations. A possibility of the appearance of a massless mode associated with fluctuations of the phase difference is also discussed. Next we show that gradients of densities and phase differences can be inextricably intertwined in vortex excitations in three-band models. This can lead to very long-range attractive intervortex interactions and the appearance of type-1.5 regimes even when the intercomponent Josephson coupling is large. In some cases it also results in the formation of a domainlike structure in the form of a ring of suppressed density around a vortex across which one of the phases shifts by p. We also show that field-induced vortices can lead to a change of broken symmetry from U(1) to U(1) x Z(2) in the system. In the type-1.5 regime, it results in a semi-Meissner state where the system has a macroscopic phase separation in domains with broken U(1) and U(1) x Z(2) symmetries.

Keyword
2-BAND SUPERCONDUCTORS
National Category
Physical Sciences
Identifiers
urn:nbn:se:kth:diva-47977 (URN)10.1103/PhysRevB.84.134518 (DOI)000296287500007 ()2-s2.0-80155184781 (Scopus ID)
Funder
Swedish Research CouncilKnut and Alice Wallenberg Foundation
Note
QC 20111117Available from: 2011-11-17 Created: 2011-11-15 Last updated: 2017-12-08Bibliographically approved
5. Topological Solitons in Three-Band Superconductors with Broken Time Reversal Symmetry
Open this publication in new window or tab >>Topological Solitons in Three-Band Superconductors with Broken Time Reversal Symmetry
2011 (English)In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 107, no 19, 197001- p.Article in journal (Refereed) Published
Abstract [en]

We show that three-band superconductors with broken time reversal symmetry allow magnetic flux-carrying stable topological solitons. They can be induced by fluctuations or quenching the system through a phase transition. It can provide an experimental signature of the time reversal symmetry breakdown.

National Category
Physical Sciences
Identifiers
urn:nbn:se:kth:diva-50313 (URN)10.1103/PhysRevLett.107.197001 (DOI)000297006100008 ()2-s2.0-80155137550 (Scopus ID)
Note
QC 20120119Available from: 2012-01-19 Created: 2011-12-05 Last updated: 2017-12-08Bibliographically approved

Open Access in DiVA

Thesis(3151 kB)463 downloads
File information
File name FULLTEXT01.pdfFile size 3151 kBChecksum SHA-512
8abc7779b27104e9ef3f826885c322a7c2af3539f8153c8a54f2980bcf6aa38a58178d71c3ef49a4f5c9b533c789792de1e1109538d169479566f36521c1acfb
Type fulltextMimetype application/pdf

Search in DiVA

By author/editor
Carlström, Johan
By organisation
Statistical Physics
Condensed Matter Physics

Search outside of DiVA

GoogleGoogle Scholar
Total: 463 downloads
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

isbn
urn-nbn

Altmetric score

isbn
urn-nbn
Total: 249 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf