My name is F. R. Pratama. I am a doctoral student at Department of Physics, Tohoku University.
I have been in Prof. Saito's group since 2016, where I came as a Master student by IGPAS program.
My current research interest is the optical absorption in two-dimensional materials.
I work closely with my tutor Dr. Ukhtary.
You can contact me by emails: pratama(at)flex.phys.tohoku.ac.jp (official), or
In this paper, we present theoretical calculation for optical transition in graphene by near-field (NF).
The calculation shows that the NF induces non-vertical optical transition, in which transfer momentum between electron and NF occurs,
as well as complete supression of vertical transition, which is the only possible case in far-field spectroscopy.
In this paper, we investigate the origins of circular dichroism (CD) and valley polarization (VP) in two-dimensional hexagonal (2DH) materials with broken time-reversal and inversion symmetries,
which is provided by the Haldane model. By using the Kubo formula, we calculate intrinsic longitudinal and transversal (Hall) conductivities of the Haldane model.
By solving boundary conditions at the 2DH material, we obtain the absorption probabilities for circularly-polarized lights, as well as the Faraday and Kerr angles.
We show that the imaginary part of the Hall conductivity determines the ellipticity of the transmitted and reflected lights (proportional to CD),
while its real part generate large Faraday and Kerr rotations (up to a few degrees). We show that our approach is also applicable to calculate the optial absorptions in silicene and transition-metal dichalcogenides.