Superconductivity induced by oxygen deficiency inLa0.85Sr0.15FeAsO1−δ

Superconductivity Induced by Negative Centers

We study the effect of random dilution of attraction centers on electron pairing in a generalization of the negative U Hubbard model where the interaction Ui, defined on the two dimensional lattice, can be −|U | and 0 with probability c and 1− c depending on the lattice site i. Using the determinant quantum Monte Carlo approach, we find the critical concentration c0 of negative centers which le...

Phonon Anomalies Induced by Superconductivity

We calculate the electronic polarizability in the superconducting state near extremum vectors ~ Q0 of the Fermi surface. A pole appears in the polarizability at frequencies ω near the superconducting gap 2∆ which leads to a sharp peak at ω just below 2∆ in the lattice vibrations near ~ Q0. A second order transition to a charge density wave state below the superconducting transition is shown to ...

Oxygen isotope effect in cuprates results from polaron-induced superconductivity

The planar oxygen isotope effect coefficient measured as a function of hole doping in the Prand La-doped YBa2Cu3O7 (YBCO) and the Ni-doped La1.85Sr0.15CuO4 (LSCO) superconductors quantitatively and qualitatively follows the form originally proposed by Kresin andWolf [Phys. Rev. B 49, 3652 (1994)], which was derived for polarons perpendicular to the superconducting planes. Interestingly, the inv...

Oxygen Deficiency in Plants

Plants, under natural or experimental conditions, can be subject to a range of O 2 concentrations from normal (normoxia) through deficient (hypoxia) to total absence (anoxia). Many metabolic processes are affected by O 2 deficiency but the most studied events are those related to respiration and metabolism of N. In the absence of a terminal electron acceptor for the electron transport chain, th...

Title Superconductivity Induced by Longitudinal Ferromagnetic Fluctuations in UCoGe