Dynamic Hubbard model: kinetic energy driven charge expulsion, charge inhomogeneity, hole superconductivity, and Meissner effect

Abstract

Dynamic Hubbard models describe the fact that the wavefunction of an electron in an atomic orbital expands when a second electron occupies the orbital. These models give rise to superconductivity driven by lowering of kinetic energy when the electronic energy band is almost full, with higher transition temperatures resulting when the ions are negatively charged. We show that the charge distribution in dynamic Hubbard models can be highly inhomogeneous in the presence of disorder, and that a finite system will expel {\it negative charge} from the interior to the surface, and that these tendencies are largest in the parameter regime where the models give rise to highest superconducting transition temperatures. High $T_c$ cuprate materials exhibit charge inhomogeneity and they exhibit tunneling asymmetry, a larger tendency to emit electrons rather than holes in NIS tunnel junctions. We propose that these properties, as well as their high $T_c$'s, are evidence that they are governed by the physics described by dynamic Hubbard models. Below the superconducting transition temperature the models considered here describe a negatively charged superfluid and positively charged quasiparticles, unlike the situation in conventional BCS superconductors where quasiparticles are charge neutral on average. We examine the temperature dependence of the superfluid and quasiparticle charges and conclude that spontaneous electric fields should be observable in the interior and in the vicinity of superconducting materials described by these models at sufficiently low temperatures. We furthermore suggest that the dynamics of the negatively charged superfluid and positively charged quasiparticles in dynamic Hubbard models can provide an explanation for the Meissner effect observed in superconducting materials.

References in corpus (12)

• Superconductivity in novel BiS2-based layered superconductor LaO1-xFxBiS2
• Visualizing the emergence of the pseudogap state and the evolution to superconductivity in a lightly hole-doped Mott insulator
• BCS theory of superconductivity: the world's largest Madoff scheme?
• Spin Meissner Effect in Superconductors and the Origin of the Meissner Effect
• The missing angular momentum of superconductors
• Do superconductors violate Lenz's law? Body rotation under field cooling and theoretical implications
• Charge expulsion, charge inhomogeneity and phase separation in dynamic Hubbard models
• Charge expulsion, Spin Meissner effect, and charge inhomogeneity in superconductors
• Correcting 100 years of misunderstanding: electric fields in superconductors, hole superconductivity, and the Meissner effect
• Prediction of unexpected behavior of the mean inner potential of superconductors
• Experimental consequences of predicted charge rigidity of superconductors
• Apparent increase in the thickness of superconducting particles at low temperatures measured by electron holography

Cited by in corpus (9)

• On the dynamics of the Meissner effect
• Effect of orbital relaxation on the band structure of cuprate superconductors and implications for the superconductivity mechanism
• Superconductivity, diamagnetism, and the mean inner potential of solids
• Electron-phonon coupling and superconductivity in the doped topological-crystalline insulator (Pb${}_{0.5}$Sn${}_{0.5}$)${}_{1-x}$In${}_x$Te
• Towards an understanding of hole superconductivity
• Dynamic Hubbard model for solids with hydrogen-like atoms
• The Meissner effect in superconductors: emergence versus reductionism
• Ferromagnetism and doublon localization in a Wannier-Hubbard chain
• The Meissner effect does not require radial charge flow