1. Condensed-Matter Physics & Materials Science Seminar

    "Electron-hole asymmetry and kinetic energy driven superconductivity in dynamic Hubbard models and real materials"

    Presented by Jorge Hirsch, University of California, San Diego

    Wednesday, February 12, 2014, 1:30 pm
    Bldg. 734, ISB Seminar Room 201 (upstairs)

    Hosted by: Yimei Zhu

    Dynamic Hubbard models are simple extensions of the conventional Hubbard model that incorporate the generic fact that electronic orbitals in atoms expand under double electron occupancy, due to electron-electron repulsion. These models are electron-hole asymmetric and lead to superconductivity when electronic energy bands are almost full. Notably, the vast majority of superconducting materials exhibit positive Hall coefficient in the normal state, suggesting that this physics plays a role. Superconductivity described by these models is kinetic-energy-driven, and the superconducting ground state exhibits macroscopic charge inhomogeneity and an electric field in the interior. We predict that this physics takes place in superconducting materials and discuss optical and electron holography experiments that can detect it. These models also explain the Meissner effect and the London moment in a straightforward way.