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SUMMARY:Imaging Ballistic Trajectory in High Mobility Graphene Sample Usin
 g Scanning Gate Microscopy - Mr Ziwei Dou ( University of Cambridge)
DTSTART:20160217T141500Z
DTEND:20160217T151500Z
UID:TALK64316@talks.cam.ac.uk
CONTACT:Teri Bartlett
DESCRIPTION:The high mobility achieved in the mesoscopic graphene devices 
 encapsulated by hexagon boron-nitride (h-BN) enables the ballistic transpo
 rt over a few micrometers and provides the opportunity to investigate the 
 novel electron optics in Dirac fermion system. The scanning gate microscop
 e (SGM) is a valuable tool to study these ballistic transport phenomena an
 d has been applied to investigate the Fabry-Perot cavity across a graphene
  np junction [1]. In this talk I will present some works extending the SGM
  technique to image the ballistic trajectories of the magnetic focusing in
  a graphene device. By locally varying the carrier concentration through t
 he charged AFM tip at 4K\, we are able to 1) image the first and second fo
 cusing arcs by diverting the focused electrons away from the collector\; a
 nd 2) refocus the slightly misaligned electrons back to collector [2]. Our
  results demonstrate the feasibility of the method and indicate the possib
 ility of manipulating ballistic electron beams with an AFM probe. Another 
 independent but similar work also supports our findings [3]
LOCATION:Mott Seminar Room (Mott Building Room 531)\, Cavendish Laboratory
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