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Superconducting and excitonic quantum phase transitions in doped Dirac electronic systems

2011; Elsevier BV; Volume: 376; Issue: 5 Linguagem: Inglês

10.1016/j.physleta.2011.12.030

1873-2429

Lizardo H.C.M. Nunes, Ricardo L. S. Farias, E. C. Marino,

Physics of Superconductivity and Magnetism

We investigate the effect of superconducting and excitonic interactions, as well as their competition, on Dirac electrons on a bipartite planar lattice. It is shown that, at half-filling, Cooper pairs and excitons coexist if the superconducting and excitonic coupling parameters are equal and above a threshold corresponding to a quantum critical point. In the case where only the excitonic interaction is present, we obtain a critical chemical potential, as a function of the interaction strength. Conversely, if only the superconducting interaction is considered, we show that the superconducting gap displays a characteristic dome as charge carriers are doped into the system. We also show that, as the chemical potential increases, superconductivity tends to suppress the excitonic order parameter.