Volume 115, Number 2, July 2016
|Number of page(s)||6|
|Section||Condensed Matter: Electronic Structure, Electrical, Magnetic and Optical Properties|
|Published online||30 August 2016|
Possible singlet and triplet superconductivity on honeycomb lattice
1 National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University Nanjing 210093, China
2 Collaborative Innovation Center of Advanced Microstructures, Nanjing University - Nanjing 210093, China
3 Department of Physics and Institute of Theoretical Physics, Nanjing Normal University - Nanjing, 210023, China
Received: 13 May 2016
Accepted: 2 August 2016
We study the possible superconducting pairing symmetry mediated by spin and charge fluctuations on the honeycomb lattice using the extended Hubbard model and the random-phase-approximation method. From 2% to 20% doping levels, a spin-singlet -wave is shown to be the leading superconducting pairing symmetry when only the on-site Coulomb interaction U is considered, with the gap function being a mixture of the nearest-neighbor and next-nearest-neighbor pairings. When the offset of the energy level between the two sublattices exceeds a critical value, the most favorable pairing is a spin-triplet f-wave which is mainly composed of the next-nearest-neighbor pairing. We show that the next-nearest-neighbor Coulomb interaction V is also in favor of the spin-triplet f-wave pairing.
PACS: 74.20.Rp – Pairing symmetries (other than s-wave) / 74.20.Mn – Nonconventional mechanisms / 71.10.Fd – Lattice fermion models (Hubbard model, etc.)
© EPLA, 2016
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