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UID:1-68@lptms.universite-paris-saclay.fr
DTSTART:20120924T100000Z
DTEND:20120924T100000Z
DTSTAMP:20120918T055356Z
URL:http://www.lptms.universite-paris-saclay.fr/seminars/soutenance-de-the
 se-tianyou-yi/
SUMMARY:Soutenance de thèse : Tianyou Yi - LPTMS-batiment 100\, salle des 
 conseils - 24 Sep 12 10:00
DESCRIPTION:Modeling of dynamical vortex states in charge density waves\nTi
 anyou Yi\, LPTMS\nElectronic Crystals is a common form of organization in 
 conducting solids. They take forms of Wigner crystals at hetero-junctions 
 and nano-wires\, charge density waves (CDWs) in chain compounds\, spin den
 sity waves in organic conductors\, stripes in doped oxides and high-Tc sup
 erconductors. In the CDW ground state\, the elementary units can be readju
 sted by absorbing or rejecting pairs of electrons. Such a phase-slip proce
 ss should go via topologically nontrivial configurations: solitons and dis
 locations – the CDW vortices. An experimental access to those states cam
 e from studies of nano-fabricated mesa-junctions\, from the STM visualizat
 ions and from the X-ray micro-diffraction.\n Following these requests\, w
 e performed a program to model the stationary states and their transient d
 ynamic for the CDW in restricted geometries under the applied field or the
  passing current. A particular care had to be taken to derive a gauge inva
 riant and current conserving scheme for the interacting condensed and norm
 al charge densities. The model takes into account multiple fields in mutua
 l nonlinear interactions: the amplitude and the phase of the CDW complex o
 rder parameter\, distributions of the electric field\, the density and the
  current of normal carriers. We have found that vortices are formed stepwi
 se in the junction when the voltage across\, or the current through\, exce
 ed a threshold. The vortex core concentrates the voltage drop\, working as
  a self-tuned microscopic tunnelling junction. The studied reconstruction 
 in junctions of the CDW is a convenient playground for modern efforts of f
 ield-effect transformations in strongly correlated materials with spontane
 ous symmetry breakings 
LOCATION:LPTMS-batiment 100\, salle des conseils\, 15 Rue Georges Clemencea
 u\, Orsay\, France
GEO:48.698200;2.181770
X-APPLE-STRUCTURED-LOCATION;VALUE=URI;X-ADDRESS=15 Rue Georges Clemenceau\,
  Orsay\, France;X-APPLE-RADIUS=100;X-TITLE=LPTMS-batiment 100\, salle des 
 conseils:geo:48.698200,2.181770
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