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Title: Analysis of Scanned Probe Images for Magnetic Focusing in Graphene

We have used cooled scanning probe microscopy (SPM) to study electron motion in nanoscale devices. The charged tip of the microscope was raster-scanned at constant height above the surface as the conductance of the device was measured. The image charge scatters electrons away, changing the path of electrons through the sample. Using this technique, we imaged cyclotron orbits that flow between two narrow contacts in the magnetic focusing regime for ballistic hBN–graphene–hBN devices. We present herein an analysis of our magnetic focusing imaging results based on the effects of the tip-created charge density dip on the motion of ballistic electrons. The density dip locally reduces the Fermi energy, creating a force that pushes electrons away from the tip. When the tip is above the cyclotron orbit, electrons are deflected away from the receiving contact, creating an image by reducing the transmission between contacts. The data and our analysis suggest that the graphene edge is rather rough, and electrons scattering off the edge bounce in random directions. However, when the tip is close to the edge, it can enhance transmission by bouncing electrons away from the edge, toward the receiving contact. Our results demonstrate that cooled SPM is a promising toolmore » to investigate the motion of electrons in ballistic graphene devices.« less
 [1] ;  [2] ;  [3] ;  [3]
  1. Harvard Univ., Cambridge, MA (United States). School of Engineering and Applied Sciences
  2. Harvard Univ., Cambridge, MA (United States). Dept. of Physics
  3. Harvard Univ., Cambridge, MA (United States). School of Engineering and Applied Sciences. Dept. of Physics
Publication Date:
Grant/Contract Number:
FG02-07ER46422; FA9550-13-1-0211
Published Article
Journal Name:
Journal of Electronic Materials
Additional Journal Information:
Journal Volume: 46; Journal Issue: 7; Journal ID: ISSN 0361-5235
Research Org:
Harvard Univ., Cambridge, MA (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22); US Air Force Office of Scientific Research (AFOSR); National Science Foundation (NSF)
Country of Publication:
United States
36 MATERIALS SCIENCE; 47 OTHER INSTRUMENTATION; scanning probe microscopy theory; ballistic transport; graphene; simulation; magnetic focusing; electron trajectories
OSTI Identifier:
Alternate Identifier(s):
OSTI ID: 1423801