Resilience of d-wave superconductivity to nearest-neighbor repulsion

D. Sénéchal; A. G. R. Day; V. Bouliane; A.-M. S. Tremblay

doi:10.1103/PhysRevB.87.075123

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Resilience of d-wave superconductivity to nearest-neighbor repulsion

D. Sénéchal, A. G. R. Day, V. Bouliane, A.-M. S. Tremblay

DOI 10.1103/PhysRevB.87.075123 · Physical Review B

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Abstract

Many theoretical approaches find d-wave superconductivity in the prototypical one-band Hubbard model for high-temperature superconductors. At strong coupling (U≥W, where U is the on-site repulsion and W=8t the bandwidth) pairing is controlled by the exchange energy J=4t2/U. One may then surmise, ignoring retardation effects, that near-neighbor Coulomb repulsion V will destroy superconductivity when it becomes larger than J, a condition that is easily satisfied in cuprates, for example. Using cellular dynamical mean-field theory with an exact diagonalization solver for the extended Hubbard model, we show that pairing at strong coupling is preserved, even when V≫J, as long as V≲U/2. While at weak coupling V always reduces the spin fluctuations and hence d-wave pairing, at strong coupling, in the underdoped regime, the increase of J=4t2/(U−V) caused by V increases binding at low frequency while the pair-breaking effect of V is pushed to high frequency. These two effects compensate in the underdoped regime, in the presence of a pseudogap. While the pseudogap competes with superconductivity, the proximity to the Mott transition that leads to the pseudogap, and retardation effects, protect d-wave superconductivity from V.