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BEGIN:VEVENT
UID:1-18@lptms.universite-paris-saclay.fr
DTSTART:20120214T110000Z
DTEND:20120214T110000Z
DTSTAMP:20120208T115951Z
URL:http://www.lptms.universite-paris-saclay.fr/seminars/seminaire-du-lptm
 s-thierry-champel/
SUMMARY:Séminaire du LPTMS: Thierry Champel - LPTMS\, salle 201\, 2ème é
 tage\, Bât 100\, Campus d'Orsay - 14 Fév 12 11:00
DESCRIPTION:Quasi-local quantum mechanics for disordered 2D electron gases 
 at high magnetic fields\nThierry Champel\, Université Joseph Fourier\nWe 
 have developed a semicoherent-state Green's function formalism which rigor
 ously describes quantum mechanical motion of an electron in a perpendicula
 r magnetic field and a 2D disordered potential landscape beyond the semi-c
 lassical guiding center picture. Our general technique is connected to the
  deformation (Weyl) quantization theory in phase space developed in mathem
 atical physics. For generic 2D quadratic potentials\, we exactly solve the
  limit of large cyclotron frequency (yet at finite magnetic length) where 
 Landau level mixing becomes negligible\, both for the ordinary two-dimensi
 onal electron gas and for graphene (relativistic dispersion). Furthermore\
 , the coherent-state representation is shown to display a hierarchy of loc
 al energy scales ordered by powers of the magnetic length and successive s
 patial derivatives of the local potential\, which allows one to devise con
 trolled approximation schemes at finite temperature for arbitrary and poss
 ibly disordered potential landscapes. As an application\, we derive genera
 l analytical expressions for the local density of states\, which allow us 
 to account for many puzzling features recently observed in high magnetic f
 ield scanning tunneling spectroscopies on semiconducting heterostructures 
 and graphene. Our recent theoretical developments in relation with percola
 tive transport at high magnetic fields will also be evoked.\nRefs.: T. Cha
 mpel and S. Florens\, PRB 80\, 125322 (2009)\; T. Champel and S. Florens\,
  PRB 82\, 045421 (2010)\; M. Flöser\, S. Florens\, and T. Champel\, PRL 1
 07\, 176806 (2011).
CATEGORIES:seminars
LOCATION:LPTMS\, salle 201\, 2ème étage\, Bât 100\, Campus d'Orsay\, 15 
 Rue Georges Clemenceau\, Orsay\, 91405\, France
GEO:48.698185;2.181768
X-APPLE-STRUCTURED-LOCATION;VALUE=URI;X-ADDRESS=15 Rue Georges Clemenceau\,
  Orsay\, 91405\, France;X-APPLE-RADIUS=100;X-TITLE=LPTMS\, salle 201\, 2è
 me étage\, Bât 100\, Campus d'Orsay:geo:48.698185,2.181768
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