MEHMET TOPSAKAL

Profile Information
Name
Dr. MEHMET TOPSAKAL
Institution
Brookhaven National Laboratory
Position
Scientist
Affiliation
Brookhaven National Laboratory
h-Index
30
ORCID
0000-0002-7880-0740
Expertise
3D Printing, Data Analysis, Spectroscopy, Synchrotron Radiation, Tomography, X-ray Absorption Spectroscopy, X-Ray Diffraction (XRD), X-ray Imaging
Presentations:
"Comparison of SXRD and Microstructure of Electron-beam Welded RPV Steels" Jasmyne Emerson, Grayson Nemets, Elliot Marrero, MEHMET TOPSAKAL, Simerjeet Gill, Janelle Wharry, Maria Okuniewski, NSLS-II, CFN, & LBMS Users’ Meeting April 24-27, (2023)
"Synchrotron X-ray Diffraction Characterization of the Phase Transformation Behaviors Induced by Electron Beam Welding in SA508 Reactor Pressure Vessel Steels" Jasmyne Emerson, Grayson Nemets, Elliot Marrero, MEHMET TOPSAKAL, Simerjeet Gill, Janelle Wharry, Maria Okuniewski, Materials in Nuclear Energy Systems (MiNES 2023) December 11-14, (2023)
Additional Publications:
"Effects of Charging and Electric Field on Graphene Oxide" Hikmet Hakan Gürel, Salim Ciraci, Mehmet Topsakal, [2013] Journal of Physical Chemistry C · DOI: 10.1021/jp310352u
"Domain formation on oxidized graphene" S. Ciraci, M. Topsakal, [2012] Physical Review B · DOI: 10.1103/physrevb.86.205402
"Effects of static charging and exfoliation of layered crystals" S. Ciraci, M. Topsakal, [2012] Physical Review B · DOI: 10.1103/physrevb.85.045121
"Frictional Figures of Merit for Single Layered Nanostructures" C. Ataca, M. Topsakal, H. Sahin, S. Ciraci, S. Cahangirov, [2012] Physical Review Letters · DOI: 10.1103/physrevlett.108.126103
"Frictional figures of merit for single layered nanostructures." [2012] Physical review letters
"Graphene coatings: An efficient protection from oxidation" H. Şahin, S. Ciraci, M. Topsakal, [2012] Physical Review B · DOI: 10.1103/physrevb.85.155445
"A Comparative Study of Lattice Dynamics of Three- and Two-Dimensional MoS(2)" M. Topsakal, E. Aktürk, S. Ciraci, C. Ataca, [2011] Journal of Physical Chemistry C · DOI: 10.1021/jp205116x
"Static charging of graphene and graphite slabs" S. Ciraci, M. Topsakal, [2011] Applied Physics Letters · DOI: 10.1063/1.3573806

The effect of external static charging of graphene and its flakes are investigated by using first-principles calculations. While the Fermi level of negatively charged graphene rises and then is quickly pinned by the parabolic, nearly free electronlike bands, it moves down readily by removal of electrons from graphene. Excess charges accumulate mainly at both surfaces of graphite slab. Even more remarkable is that Coulomb repulsion exfoliates the graphene layers from both surfaces of positively charged graphite slab. The energy level structure, binding energy, and spin-polarization of specific adatoms adsorbed to a graphene flake can be monitored by charging.

"Structures of fluorinated graphene and their signatures" M. Topsakal, S. Ciraci, H. Şahin, [2011] Physical Review B · DOI: 10.1103/physrevb.83.115432
"Armchair nanoribbons of silicon and germanium honeycomb structures" M. Topsakal, S. Ciraci, S. Cahangirov, [2010] Physical Review B · DOI: 10.1103/physrevb.81.195120
"Current-voltage (I-V) characteristics of armchair graphene nanoribbons under uniaxial strain" V. M. K. Bagci, S. Ciraci, M. Topsakal, [2010] Physical Review B · DOI: 10.1103/physrevb.81.205437
"Elastic and plastic deformation of graphene, silicene, and boron nitride honeycomb nanoribbons under uniaxial tension: A first-principles density-functional theory study" S. Ciraci, M. Topsakal, [2010] PHYSICAL REVIEW B · DOI: 10.1103/physrevb.81.024107
"First-principles study of defects and adatoms in silicon carbide honeycomb structures" M. Topsakal, S. Cahangirov, S. Ciraci, E. Bekaroglu, [2010] PHYSICAL REVIEW B · DOI: 10.1103/physrevb.81.075433
"Long-range interactions in carbon atomic chains" M. Topsakal, S. Ciraci, S. Cahangirov, [2010] Physical Review B · DOI: 10.1103/physrevb.82.195444
"The response of mechanical and electronic properties of graphane to the elastic strain" S. Cahangirov, S. Ciraci, M. Topsakal, [2010] APPLIED PHYSICS LETTERS · DOI: 10.1063/1.3353968

Based on first-principles calculations, we resent a method to reveal the elastic properties of recently synthesized monolayer hydrocarbon, graphane. The in-plane stiffness and Poisson’s ratio values are found to be smaller than those of graphene, and its yielding strain decreases in the presence of various vacancy defects and also at high ambient temperature. We also found that the band gap can be strongly modified by applied strain in the elastic range.

"First-principles study of two- and one-dimensional honeycomb structures of boron nitride" E. Aktürk, S. Ciraci, M. Topsakal, [2009] PHYSICAL REVIEW B · DOI: 10.1103/physrevb.79.115442
"First-principles study of zinc oxide honeycomb structures" S. Cahangirov, E. Bekaroglu, S. Ciraci, M. Topsakal, [2009] PHYSICAL REVIEW B · DOI: 10.1103/physrevb.80.235119
"Monolayer honeycomb structures of group-IV elements and III-V binary compounds: First-principles calculations" S. Cahangirov, M. Topsakal, E. Bekaroglu, E. Akturk, R. T. Senger, S. Ciraci, H. Şahin, [2009] PHYSICAL REVIEW B · DOI: 10.1103/physrevb.80.155453
"Two- and One-Dimensional Honeycomb Structures of Silicon and Germanium" M. Topsakal, E. Aktürk, H. Şahin, S. Ciraci, S. Cahangirov, [2009] PHYSICAL REVIEW LETTERS · DOI: 10.1103/physrevlett.102.236804
"Electronic and magnetic properties of 3d transition-metal atom adsorbed graphene and graphene nanoribbons" M. Topsakal, E. Durgun, S. Ciraci, H. Sevinçli, [2008] PHYSICAL REVIEW B · DOI: 10.1103/physrevb.77.195434
"First-principles approach to monitoring the band gap and magnetic state of a graphene nanoribbon via its vacancies" E. Aktürk, H. Sevinçli, S. Ciraci, M. Topsakal, [2008] PHYSICAL REVIEW B · DOI: 10.1103/physrevb.78.235435
"Spin confinement in the superlattices of graphene ribbons" H. Sevinçli, S. Ciraci, M. Topsakal, [2008] APPLIED PHYSICS LETTERS · DOI: 10.1063/1.2919525

Based on first-principles calculations, we showed that repeated heterostructures of zigzag graphene nanoribbons of different widths form multiple quantum well structures. Edge states of specific spin directions can be confined in these wells. The electronic and magnetic state of the ribbon can be modulated in real space. In specific geometries, the absence of reflection symmetry causes the magnetic ground state of whole heterostructure to change from antiferromagnetic to ferrimagnetic. These quantum structures of different geometries provide unique features for spintronic applications.

"Superlattice structures of graphene-based armchair nanoribbons" M. Topsakal, S. Ciraci, H. Sevinçli, [2008] PHYSICAL REVIEW B · DOI: 10.1103/physrevb.78.245402
Source: ORCID/CrossRef using DOI