uu.seUppsala University Publications
Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association
  • 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
Point defects in the (d+id)-wave superconducting state of heavily doped graphene
Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
2013 (English)Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
Abstract [en]

Previous studies have suggested that the material graphene might transition into an electron-electron interaction driven, unconventional, time-reversal-symmetry-breaking, (d+id)wave superconducting state upon either significant electron or hole doping, and, in particular, upon doping to the Van Hove singularity. As defects are likely to be introduced in the doping process, we are, in this text, concerned with the effects of defects on this superconducting state near the Van Hove singularity doping. To investigate the effects we use a mean-field treatment of a phenomenological resonant-valence-bond model. We find that the resonant-valence-bond amplitudes, which in the defect free graphene sheet are proportional to the superconducting pairing-potential, are suppressed near the defects, and that the recovery is well described by an exponential, yet anisotropic, recovery. In general, we find that the (d+id)-wave, superconducting state is quite resilient, and that even for strong defects, such as a vacancy, the recovery length is of the order of one lattice constant when extrapolated to weak pairing-potentials; this is compared to a conventional superconducting state of an attractive Hubbard model for which the same decay length is found to be of the order of a half lattice constant. For the defect free graphene sheet the (d+id)-wave state is a completely gapped state. The introduction of vacancies is, however, found to be accompanied by the appearance of midgap states. These states are shown to be localized around the vacancies. In accordance with the nature of this text, we will, for the benefit of students and non-experts, include an introductory section on the fundamental methods and concepts used. It gives a short and hopefully pedagogical introduction to the rudimentary concepts of solid state theory and the microscopic BCS theory of superconductivity.

Place, publisher, year, edition, pages
2013. , 96 p.
Series
FYSAST, FYSMAS1005
Keyword [en]
Graphene, Superconductivity, Defects, Van Hove singularity
National Category
Condensed Matter Physics
Identifiers
URN: urn:nbn:se:uu:diva-213212OAI: oai:DiVA.org:uu-213212DiVA: diva2:681382
Educational program
Master Programme in Physics
Supervisors
Examiners
Available from: 2014-02-05 Created: 2013-12-19 Last updated: 2014-02-05Bibliographically approved

Open Access in DiVA

fulltext(4536 kB)189 downloads
File information
File name FULLTEXT01.pdfFile size 4536 kBChecksum SHA-512
70db96c419ce2ade5dd8c7a0b63926d37744e1f25917ab9af7a2c3d531d0511533ce494347b69af35a8bbff135d5bb47f918a50ee1a11435dd4487638c11d691
Type fulltextMimetype application/pdf

By organisation
Department of Physics and Astronomy
Condensed Matter Physics

Search outside of DiVA

GoogleGoogle Scholar
Total: 189 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

urn-nbn

Altmetric score

urn-nbn
Total: 466 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association
  • 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