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DTSTART:20180325T030000
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DTSTART:20171029T020000
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DTSTAMP:20260406T075437Z
UID:5aa6469252627227530075@ist.ac.at
DTSTART:20180322T090000
DTEND:20180322T100000
DESCRIPTION:Speaker: Fereshte Ghahari\nhosted by Georgios Katsaros\nAbstrac
 t: Recent progress in creating and probing graphene quantum dots (QDs) wit
 h fixed build-in potentials has offered a new platform to investigate Klei
 n tunneling related phenomena. In this talk\, I describe scanning tunnelin
 g spectroscopy measurements of the energy spectrum of graphene QDs as a fu
 nction of energy\, spatial position\, and magnetic field. In the absence o
 f a magnetic field\, confinement of graphene carriers in a p-n junction re
 sonator gives rise to a series of quasi-bound single particle states which
  result from oblique Klein scattering at the p-n interface. Applying a wea
 k magnetic field\, we observe a giant and discontinuous change in the ener
 gy of time-reversed angular-momentum states\, which manifests itself as th
 e appearance of “new” resonances in the tunneling density of states. T
 his behavior corresponds to the on/off switching of a π- Berry phase when
  a weak critical magnetic field is reached.  With increased applied magne
 tic field\, the QD states can be confined even further as they condense in
 to highly degenerate Landau levels providing the first spatial visualizati
 on of the interplay between spatial and magnetic confinement. This is obse
 rved as formation of the seminal wedding-cake structures of concentric com
 pressible and incompressible density rings in strong magnetic fields.
LOCATION:Mondi Seminar Room 2\, Central Building\, ISTA
ORGANIZER:pdelreal@ist.ac.at
SUMMARY:Fereshte Ghahari: Quantized States\, Berry Phases\, and Quantum-Hal
 l Wedding-Cake structures in Graphene Quantum Dots
URL:https://talks-calendar.ista.ac.at/events/1182
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