Evidence for spin-triplet odd-parity superconductivity close to type-II van Hove singularities
Abstract
Searching for unconventional Cooper pairing states has been at the heart of superconductivity research since the discovery of BCS superconductors. In particular, spin-triplet odd-parity pairing states were recently revisited due to the possibility of tuning towards topological superconductors. In this context, it is interesting to note a recent proposal that such a spin-triplet pairing instability occurs when the band filling is near van Hove singularities (vHS) associated with momenta away from time-reversal invariant momenta named type-II vHS. However, this result was obtained within a weak coupling renormalization group with Fermi surface patch approximation. To explore superconducting instabilities beyond this weak coupling Fermi surface patch approximation, we perform systematic study on the Hubbard model in a two-dimensional square lattice using three different methods: random phase approximation, large-scale dynamical mean-field theory simulations with continuous time quantum Monte Carlo (CTQMC) impurity solver, and large-scale dynamical cluster simulations with the CTQMC cluster solver. We find, in a wide doping range centered around the type-II van Hove filling, a twofold degenerate, spin-triplet, odd-parity p -wave pairing state emerges due to repulsive interaction, when the Fermi surface is not sufficiently nested. Possible relevance of our findings to the recently discovered superconductors LaO1 -xFxBiS2 ,Ir1 -xPtxTe2 , and proposed doped BC3 are also discussed.
- Publication:
-
Physical Review B
- Pub Date:
- May 2015
- DOI:
- 10.1103/PhysRevB.91.184509
- arXiv:
- arXiv:1408.1407
- Bibcode:
- 2015PhRvB..91r4509M
- Keywords:
-
- 74.40.Kb;
- 71.10.Fd;
- 74.72.-h;
- 71.10.Hf;
- Lattice fermion models;
- Cuprate superconductors;
- Non-Fermi-liquid ground states electron phase diagrams and phase transitions in model systems;
- Condensed Matter - Superconductivity;
- Condensed Matter - Strongly Correlated Electrons
- E-Print:
- 9 pages, 9 figures