Apr 26, 2000
Imaging the Effects on Superconductivity of Individual Impurity Atoms
Professor J. C. Seamus Davis, University of California, Berkeley
Dr. Davis will describe his recent studies of the High-TC Superconductor
BiSrCaCuO, using a high resolution very low temperature STM, in which
single impurity atoms were used to probe the structure of the
superconducting order parameter and the correlation between electrons.
Quasiparticle scattering at impurities generates localized impurity states
at the atmoic scale. Imaging these impurity states with individual
(non-magnetic) Zinc dopant atoms at the Copper site in the Copper-Oxide
plane shows several direct real-space consequences of the d-wave nature of
the order parameter. The spectra are in qualitative agreement with d-wave
BCS theories of non-magnetic quasiparticle scattering at a single impurity
atom. The destruction of superconductivity within 1.5 nm of the Zn sites
is observed. He will also discuss very new results of imaging of the
impurity states associated with individual Nickel dopant atoms (magnetic)
substituted at the Copper site, which show numerous new atomic-scale
phenomena which, although partially consistent with theory for magnetic
impurity atom scattering in a d-wave BCS context, are not fully described
by existing theories.
Audio for this talk requires sound hardware, and RealPlayer or RealAudio
by RealNetworks.
Begin continuous audio for the whole
talk. (Or, download the whole audio file.)
Author entry (protected)
