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Chiral d-wave superconductivity on the honeycomb lattice close to the Mott state
Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
2014 (English)In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 90, no 5, 054521- p.Article in journal (Refereed) Published
Abstract [en]

We study superconductivity on the honeycomb lattice close to the Mott state at half filling. Due to the sixfold lattice symmetry and disjoint Fermi surfaces at opposite momenta, we show that several different fully gapped superconducting states naturally exist on the honeycomb lattice, of which the chiral d + id'-wave state has previously been shown to appear when superconductivity appears close to the Mott state. Using renormalized mean-field theory to study the t-J model and quantum Monte Carlo calculations of the Hubbard-U model we show that the d + id'-wave state is the favored superconducting state for a wide range of on-site repulsion U, from the intermediate to the strong coupling regime. We also investigate the possibility of a mixed chirality d-wave state, where the overall chirality cancels. We find that a state with d + id'-wave symmetry in one valley but d - id'-wave symmetry in the other valley is not possible in the t-J model without reducing the translational symmetry, due to the zero-momentum and spin-singlet nature of the superconducting order parameter. Moreover, any extended unit cells result either in disjoint Dirac points, which cannot harbor this mixed chirality state, or the two valleys are degenerate at the zone center, where valley hybridization prevents different superconducting condensates. We also investigate extended unit cells where the overall chirality cancels in real space. For supercells containing up to eight sites, including the Kekule distortion, we find no energetically favorable d-wave solution with an overall zero chirality within the restriction of the t-J model.

Place, publisher, year, edition, pages
2014. Vol. 90, no 5, 054521- p.
National Category
Condensed Matter Physics
URN: urn:nbn:se:uu:diva-233015DOI: 10.1103/PhysRevB.90.054521ISI: 000341258300004OAI: oai:DiVA.org:uu-233015DiVA: diva2:753592
Available from: 2014-10-08 Created: 2014-09-29 Last updated: 2014-10-08Bibliographically approved

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Black-Schaffer, Annica M.
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