Charge Density Wave Order in Cuprate Superconductors Studied by Resonant Soft X-ray Scattering

Abstract

Cuprate high temperature superconductors have been the subject of intense investigation since their discovery in 1986. The nature of the pairing mechanism in these unconventional superconductors does not seem to be mediated by phonons, as in conventional superconductors, and thus remains a puzzle. The superconducting phase emerges from doping holes (or electrons) into the copper oxide planes of an anti-ferromagnetic Mott insulator, producing a wealth of electronic ordering phenomena in many of the cuprate families. One of these phases is an incommensurate charge ordered state, known since the mid 90's to occur in La-based cuprates along with incommensurate spin ordering and compete with superconductivity. Recent advances in experimental capabilities, notably the ability to perform resonant diffraction experiments with soft x-rays, which can be made sensitive to holes in Cu 3d and O 2p orbitals, have provided new opportunities to learn about these charge ordered states. The study of charge order in cuprate superconductors by resonant soft x-ray scattering is the subject of this thesis.