April 2019

Dr. Abdullah, Seminar “Electronic and transport properties of locally delaminated bilayer graphene”

4/18/2019
  • PRESENTER:   Dr. Hasan M. Abdullah

    INSTITUTE:     Phys. Dept., KFUPM, Dhahran, Saudi Arabia​

    DATE:            Thursday, April 18, 2019

    TIME:             2:00 PM - 3:30 PM

    LOCATION:     B2/L5/R5209


 

Electronic and transport properties of locally delaminated bilayer graphene.


ABSTRACT

Since the first isolation of single layer graphene in 2004, graphene and its multilayers have engendered an avalanche of interest due to their astonishing optical, electronic and mechanical properties.  Recent experiments showed that   bilayer graphene samples might have domain walls separating regions with different interlayer coupling. In this talk, we will explore the transport properties, confinement and collimation of electrons in such systems. Using the four band model along with the transfer matrix, we show that the electron transmission exhibits a valley-dependent layer asymmetry and that the domain walls have a considerable effect on the chiral tunneling properties of the charge carriers. Such structures can also exhibit a strong layer selectivity when current flows through double domain walls and this selectivity can be tuned by means of electrostatic gating.  We propose that a system of a circular domain wall with a blister at the center can provide a perfect electrostatic confinement which is hindered by the so called Klein tunneling in single layer graphene. This confinement is layer localized and can be tuned by a global electrostatic gate. Finally, using a semi-classical approach and wave-packet dynamics we show that these van der Waals domain walls in bilayer graphene can be used to generate highly collimated electron beams which can be steered by a magnetic field. This might help the quest for the next generation of graphene electron-optics technology based on the concept of electron collimation such as the two dimensional Dirac fermion microscope.



BIOGRAPHY

Hasan M. Abdullah Received his B.Sc. in physics from Taiz University, Yemen in 2007. Then worked as a lecturer in Physics Department, College of Applied Sciences, Taiz University, for three years. Afterwards, he obtained his M.Sc. in physics from King Fahd University of Petroleum and Minerals (KFUPM), Saudi Arabia in 2014. Right after completing his master’s degree, he got a scholarship to pursue his Ph.D. in the same university and graduated in November, 2018. During his Ph.D. he was jointly supervised by Prof. Hocine Bahouli (KFUPM) and Prof. Francois Peeters (Antwerp University) and worked on transport properties, confinement and collimation through domain walls in bilayer graphene. His research interest focuses on transport properties and quantum dots in 2D materials, especially graphene and its multilayers.