7,954 research outputs found

    Microscopic Inhomogeneity and Superconducting Properties of a Two-dimensional Hubbard Model for High-TcT_c Cuprate

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    Recent scanning tunneling microscopy measurements on cuprate superconductors have revealed remarkable spatial inhomogeneities in the single-particle energy gap. Using cellular dynamical mean-field theory, we study the zero temperature superconducting properties of a single-band Hubbard model with a spatial modulation of the electron density. We find that the inhomogeneity in the electronic structure results in a substantial spatial variation in the superconducting order parameter and single-particle energy gap, reminiscent of the experimental results. In particular, we find that the order parameter and gap amplitudes in the hole-rich regions are significantly enhanced over the corresponding quantities in a uniform system, if the hole-rich regions are embedded in regions with smaller hole density.Comment: 6 pages, 4 figures, and 2 table

    Enhanced Superconductivity in Superlattices of High-TcT_c Cuprates

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    The electronic properties of multilayers of strongly correlated models for cuprate superconductors are investigated using cluster dynamical mean-field techniques. We focus on combinations of underdoped and overdoped layers and find that the superconducting order parameter in the overdoped layers is enhanced by the proximity effect of the strong pairing scale originating from the underdoped layers. The enhanced order parameter can even exceed the maximum value in uniform systems. This behavior is well reproduced in slave-boson mean-field calculations which also find higher transition temperatures than in the uniform system.Comment: 4 pages, 4 figure

    Coexistence of strong nematic and superconducting correlations in a two-dimensional Hubbard model

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    Using a dynamic cluster quantum Monte Carlo approximation, we study a two-dimensional Hubbard model with a small orthorhombic distortion in the nearest neighbor hopping integrals. We find a large nematic response in the low-frequency single-particle scattering rate which develops with decreasing temperature and doping as the pseudogap region is entered. At the same time, the d-wave superconducting gap function develops an s-wave component and its amplitude becomes anisotropic. The strength of the pairing correlations, however, is found to be unaffected by the strong anisotropy, indicating that d-wave superconductivity can coexist with strong nematicity in the system.Comment: 4 pages, 4 figures, published as PRB 84, 220506(R) (2011

    Preface: The Nature and Necessity of Hospitality

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    As Thomas Maier writes, hospitality is β€œa willingness to receive others when they are in need, an authentic desire to lead and serve others with a specific orientation toward the common good.” Hospitality entails sharing ourselves with others and addressing the needs of people who are marginalized in our society. It therefore promotes equality. The aspects of servant leadership that hospitality requires are discussed
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