Superconducting and excitonic quantum phase transitions in doped Dirac electronic systems |
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Authors: | Lizardo H.C.M. Nunes Ricardo L.S. FariasEduardo C. Marino |
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Affiliation: | a Departamento de Ciências Naturais, Universidade Federal de São João del Rei, 36301-000 São João del Rei, MG, Brazil b Instituto de Física, Universidade Federal do Rio de Janeiro, Caixa Postal 68528, Rio de Janeiro, RJ, 21941-972, Brazil |
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Abstract: | 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. |
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Keywords: | Dirac electrons Superconductivity Excitons Quantum criticality |
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