Abstract
We reveal an edge spin triplet p-wave superconducting pairing correlation in slightly doped zigzag graphene nanoribbons. By employing a method that combines random-phase approximation, the finite-temperature determinant quantum Monte Carlo approach, and the ground-state constrained-path quantum Monte Carlo method, it is shown that such a spin-triplet pairing is mediated by the ferromagnetic fluctuations caused by the flat band at the edge. The spin susceptibility and effective pairing interactions at the edge strongly increase as the on-site Coulomb interaction increases, indicating the importance of electron-electron correlations. It is also found that the doping-dependent ground-state p-wave pairing correlation bears some similarity to the famous superconducting dome in the phase diagram of a high-temperature superconductor, while the spin correlation at the edge is weakened as the system is doped away from half filling.
Highlights
Triplet superconductivity (SC) has been a focus of modern condensed matter physics because of its possible connection to topological quantum information and computation[1,2,3,4,5,6,7,8,9,10]
We reveal a possible edge-spin triplet p-wave superconducting pairing correlation in slightly doped zigzag graphene nanoribbons with appropriate interactions
Experimental advances in doping methods have made it possible to change the type of carriers[19,20], opening the doors for exotic phases, such as SC and magnetism induced by repulsive interactions
Summary
Triplet superconductivity (SC) has been a focus of modern condensed matter physics because of its possible connection to topological quantum information and computation[1,2,3,4,5,6,7,8,9,10]. Experimental advances in doping methods have made it possible to change the type of carriers (electrons or holes)[19,20], opening the doors for exotic phases, such as SC and magnetism induced by repulsive interactions. The proposed magnetism is similar to the flat-band ferromagnetism appearing in the orbital-active optical honeycomb lattice[33], where the band flatness dramatically amplifies the interaction effect, driving the ferromagnetic transition even with a relatively weak repulsive interaction From these discoveries, a question which naturally arises: is there is triplet SC mediated by the FM spin correlations on each edge in the doped zigzag graphene nanoribbons?. Our unbiased results show that both the ferromagnetic spin correlation and the effective p-wave superconducting pairing correlation are greatly enhanced as the interaction increases
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