Haldun Sevincli

Haldun Sevincli
Izmir Institute of Technology · Department of Materials Science and Engineering

PhD

About

63
Publications
7,606
Reads
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2,383
Citations
Citations since 2016
23 Research Items
1336 Citations
2016201720182019202020212022050100150200
2016201720182019202020212022050100150200
2016201720182019202020212022050100150200
2016201720182019202020212022050100150200
Additional affiliations
December 2019 - present
Izmir Institute of Technology
Position
  • Professor
November 2013 - present
Izmir Institute of Technology
Position
  • Professor (Associate)
April 2011 - October 2013
Technical University of Denmark
Position
  • Individual Post Doc

Publications

Publications (63)
Article
Full-text available
In the context of graphene-based composite applications, a complete understanding of charge conduction in multilayer reduced graphene oxides (rGO) is highly desirable. However, these rGO compounds are characterized by multiple and different sources of disorder depending on the chemical method used for their synthesis. Most importantly, the precise...
Preprint
In the context of graphene-based composite applications, a complete understanding of charge conduction in multilayer reduced graphene oxides (rGO) is highly desirable. However, these rGO compounds are characterized by multiple and different sources of disorder depending on the chemical method used for their synthesis. Most importantly the precise r...
Article
Ballistic transport and thermoelectric properties of group III-VI compounds (XY: X = B, Al, Ga, In, Tl; Y = O, S, Se, Te, Po) are investigated based on first-principles calculations and Landauer formalism. This large family is composed of 25 compounds which stands out with their unique electronic band structures. Mexican hat shaped valence band, wh...
Article
In this work, ab initio calculations based on density functional theory and the Landauer formalism are carried out to investigate ballistic thermoelectric properties of T−HfSe2 nanoribbons (NRs). The zigzag-edged NRs are metallic, and they are not included in this study. The armchair NRs possess two types of edge symmetries depending on the number...
Article
Photoisomeric molecules rearrange their structure when exposed to light, which alters their chemical, electronic, mechanical, as well as vibrational properties. The present study explores the possibilities to tune the thermal transport across molecular junctions by using photoisomeric molecules. The effect of isomeric switching on phonon transport...
Article
Graphene antidot lattices (GALs) are two-dimensional (2D) monolayers with periodically placed holes in otherwise pristine graphene. We investigate the electronic properties of symmetric and asymmetric GAL structures having hexagonal holes, and show that anisotropic 2D GALs can display a dimensional crossover such that effectively one-dimensional (1...
Preprint
Graphene antidot lattices (GALs) are two-dimensional (2D) monolayers with periodically placed holes in otherwise pristine graphene. We investigate the electronic properties of symmetric and asymmetric GAL structures having hexagonal holes, and show that anisotropic 2D GALs can display a dimensional crossover such that effectively one-dimensional (1...
Article
In this paper, we perform a systematic study on the electronic, magnetic, and transport properties of the hexagonal graphene quantum dots (GQDs) with armchair edges in the presence of a charged impurity using two different configurations: (1) a central Coulomb potential and (2) a positively charged carbon vacancy. The tight-binding and the half-fil...
Article
The newly synthesized two-dimensional polyaniline (C3N) is structurally similar to graphene and has interesting electronic, magnetic, optical, and thermal properties. Motivated by the fact that point defects in graphene give rise to interesting features, like magnetization in an all carbon material, we perform density functional theory calculations...
Preprint
The newly synthesized two-dimensional polyaniline (C3N) is structurally similar to graphene, and has interesting electronic, magnetic, optical, and thermal properties. Motivated by the fact that point defects in graphene give rise to interesting features, like magnetization in an all carbon material, we perform density functional theory calculation...
Preprint
Full-text available
In this paper, we perform a systematic study on the electronic, magnetic, and transport properties of the hexagonal graphene quantum dots (GQDs) with armchair edges in the presence of a charged impurity using two different configurations: (1) a central Coulomb potential and (2) a positively charged carbon vacancy. The tight binding (TB) and the hal...
Article
Combining first-principles calculations with Landauer-Büttiker formalism, ballistic thermoelectric transport properties of semiconducting two-dimensional transition metal dichalcogenides (TMDs) and oxides (TMOs) (namely MX2 with M = Cr, Mo, W, Ti, Zr, Hf; X = O, S, Se, Te) are investigated in their 2H and 1T phases. Having computed structural, as w...
Article
With the advances in fabrication of materials with feature sizes at the order of nanometers, it has been possible to alter their thermal transport properties dramatically. Miniaturization of device size increases the power density in general, hence faster electronics require better thermal transport, whereas better thermoelectric applications requi...
Article
We propose a method to engineer the phonon thermal transport properties of low dimensional systems. The method relies on introducing a predetermined combination of molecular adsorbates, which give rise to antiresonances at frequencies specific to the molecular species. Despite their dissimilar transmission spectra, thermal resistances due to indivi...
Article
We set up an evolutionary algorithm combined with density functional tight-binding (DFTB) calculations to investigate hydrogen adsorption on flat graphene and graphene monolayers curved over substrate steps. During the evolution, candidates for the new generations are created by adsorption of an additional hydrogen atom to the stable configurations...
Article
Using first-principles density functional theory calculations, we investigate a family of stable two-dimensional crystals with chemical formula A2B2, where A and B belong to groups IV and V, respectively (A=C, Si, Ge, Sn, Pb; B=N, P, As, Sb, Bi). Two structural symmetries of hexagonal lattices P6¯m2 and P3¯m1 are shown to be dynamically stable, nam...
Preprint
Using first-principles density functional theory calculations, we investigate a family of stable two-dimensional crystals with chemical formula A2B2, where A and B belong to groups IV and V, respectively (A = C, Si, Ge, Sn, Pb; B = N, P, As, Sb, Bi). Two structural symmetries of hexagonal lattices P ¯ 6m2 and P ¯ 3m1 are shown to be dynamically sta...
Preprint
Full-text available
We set up an evolutionary algorithm combined with density functional tight-binding (DFTB) calculations to investigate hydrogen adsorption on flat graphene and graphene monolayers curved over substrate steps. During the evolution, candidates for the new generations are created by adsorption of an additional hydrogen atom to the stable configurations...
Preprint
Full-text available
Using first-principles density functional theory calculations, we investigate a family of stable two-dimensional crystals with chemical formula $A_2B_2$, where $A$ and $B$ belong to groups IV and V, respectively ($A$ = C, Si, Ge, Sn, Pb; $B$ = N, P, As, Sb, Bi). Two structural symmetries of hexagonal lattices $P\bar{6}m2$ and $P\bar{3}m1$ are shown...
Article
Full-text available
We propose a method to engineer the phonon thermal transport properties of low dimensional systems. The method relies on introducing a predetermined combination of molecular adsorbates on the surface, which give rise to antiresonances at frequencies specific to the molecular species. Despite their dissimilar transmission spectra, thermal resistance...
Article
Full-text available
The integrity of phonon transport properties of large graphene (linear and curved) grain boundaries (GBs) is investigated under the influence of structural and dynamical disorder. To do this, density functional tight-binding (DFTB) method is combined with atomistic Green's function technique. The results show that curved GBs have lower thermal cond...
Article
The critical points and the corresponding singularities in the density of states of crystals were first classified by Van Hove with respect to their dimensionality and energy-momentum dispersions. Here, different from saddle-point Van Hove singularities, the occurrence of a continuum of critical points, which give rise to strong singularities in tw...
Article
Electronic, phononic, and thermoelectric transport properties of single layer black- and blue-phosphorene structures are investigated with first-principles based ballistic electron and phonon transport calculations employing hybrid functionals. The maximum values of room temperature thermoelectric figure of merit, ZT corresponding to armchair and z...
Article
Full-text available
Electron, phonon, and thermoelectric transport properties of α-, β-, γ-, and 6,6,12-graphyne sheets are compared and contrasted with those of graphene. α-, β-, and 6,6,12-graphynes, with direction dependent Dirac dispersions, have higher electronic transmittance than graphene. γ-graphyne also attains better electrical conduction than graphene excep...
Article
Full-text available
We calculate the effect on phonon transport of substrate-induced bends in graphene. We consider bending induced by an abrupt kink in the substrate, and provide results for different step-heights and substrate interaction strengths. We find that individual substrate steps reduce thermal conductance in the range between 5% and 47%. We also consider t...
Article
Full-text available
Quantum interference (QI) phenomena between electronic states in molecular circuits offer a new opportunity to design new types of molecular devices such as molecular sensors, interferometers, and thermoelectric devices. Controlling the QI effect is a key challenge for such applications. For the development of single molecular devices employing QI...
Article
Full-text available
Quantum interference (QI) effects in molecular devices have drawn increasing attention over the past years due to their unique features observed in the conductance spectrum. For the further development of single molecular devices exploiting QI effects, it is of great theoretical and practical interest to develop simple methods controlling the emerg...
Article
Full-text available
We propose a hybrid nano-structuring scheme for tailoring thermal and thermoelectric transport properties of graphene nanoribbons. Geometrical structuring and isotope cluster engineering are the elements that constitute the proposed scheme. Using first-principles based force constants and Hamiltonians, we show that the thermal conductance of graphe...
Article
Full-text available
Recently the interest in quantum interference (QI) phenomena in molecular devices (molecular junctions) has been growing due to the unique features observed in the transmission spectra. In order to design single molecular devices exploiting QI effects as desired, it is necessary to provide simple rules for predicting the appearance of QI effects su...
Data
Full-text available
Supplementary Information. A bottom-up route to enhance thermoelectric figures of merit in graphene nanoribbons
Article
Full-text available
Topology is familiar mostly from mathematics, but also natural sciences have found its concepts useful. Those concepts have been used to explain several natural phenomena in biology and physics, and they are particularly relevant for the electronic structure description of topological insulators and graphene systems. Here, we introduce topologicall...
Chapter
Full-text available
With the synthesis of a single atomic plane of graphite, namely, graphene honeycomb structure, a new perspective for carbon-based electronics is opened. The one-dimensional graphene nanoribbons (GNRs) have different band-gap values depending on their edge shape and width. In this contribution, we report our results showing that repeated heterostruc...
Article
Full-text available
We investigate within a coarse-grained model the conditions leading to the appearance of Fano resonances or anti-resonances in the conductance spectrum of a generic molecular junction with a side group (T-junction). By introducing a simple graphical representation (parabolic diagram), we can easily visualize the relation between the different elect...
Article
Graphene has a multitude of striking properties that make it an exceedingly attractive material for various applications, many of which will emerge over the next decade. However, one of the most promising applications lie in exploiting its peculiar electronic properties which are governed by its electrons obeying a linear dispersion relation. This...
Article
Outstanding thermal transport properties of carbon nanotubes (CNTs) qualify them as possible candidates to be used as thermal management units in electronic devices. However, significant variations in the thermal conductivity (κ) measurements of individual CNTs restrict their utilizations for this purpose. In order to address the possible sources o...
Article
Full-text available
We theoretically investigate the phonon propagation and thermal conductivity κ in hybrid boron nitride and graphene sheets. By using a real-space Kubo-computational transport scheme, large and disordered graphene structures are simulated, introducing disk-shaped domains with varying sizes of 2 to 8 nm and concentrations ranging from 0% to 100%. A s...
Article
The influence of the structural details and defects on the thermal transport properties of carbon nanotubes (CNTs) are explored by molecular dynamics and real-space Kubo methodologies. A variety of randomly oriented and distributed defects, (mono- and di-vacancies, Stone Wales defects) on lattice thermal conductivity and anharmonic phonon mean free...
Article
Full-text available
We investigate electron and phonon transport through edge disordered graphene nanoribbons. Electronic transport is calculated using Green's functions[1] while for phonons we develop an efficient linear scaling method [2-3] which is based on the Chebyshev polynomial expansion of the time evolution operator and the Lanczos tridiagonalization scheme....
Article
The influence of the structural detail and defects on the thermal and electronic transport properties of graphene nanoribbons (GNRs) is explored by molecular dynamics and non-equilibrium Green's function methods. A variety of randomly oriented and distributed defects, single and double vacancies, Stone-Wales defects, as well as two types of edge fo...
Article
Full-text available
An efficient order$-N$ real-space Kubo approach is developed for the calculation of the thermal conductivity of complex disordered materials. The method, which is based on the Chebyshev polynomial expansion of the time evolution operator and the Lanczos tridiagonalization scheme, efficiently treats the propagation of phonon wave-packets in real-spa...
Article
Full-text available
We have developed an efficient order-N real-space Kubo approach for the calculation of the phonon conductivity which outperforms state-of-the-art alternative implementations based on the Green's function formalism. The method treats efficiently the time-dependent propagation of phonon wave packets in real space, and this dynamics is related to the...
Article
Full-text available
We propose a possible route to achieve high thermoelectric efficiency in molecular junctions by combining a local chemical tuning of the molecular electronic states with the use of semiconducting electrodes. The former allows to control the position of the highest-occupied molecular orbital (HOMO) transmission resonance with respect to the Fermi en...
Article
Full-text available
We investigate electron and phonon transport through edge disordered zigzag graphene nanoribbons based on the same methodological tool of nonequilibrium Green functions. We show that edge disorder dramatically reduces phonon thermal transport while being only weakly detrimental to electronic conduction. The behavior of the electronic and phononic e...
Article
Full-text available
We propose a possible route to achieve high thermoelectric efficiency in molecular junctions by combining a local chemical tuning of the molecular electronic states with the use of semiconducting electrodes. The former allows to control the position of the HOMO transmission resonance with respect to the Fermi energy while the latter fulfills a twof...
Article
Full-text available
Charge and thermal conductivities are the most important parameters of carbon nanomaterials as candidates for future electronics. In this paper we address the effects of Anderson type disorder in long semiconductor carbon nanotubes (CNTs) to electron charge conductivity and lattice thermal conductivity using the atomistic Green function approach. T...
Article
Full-text available
Based on first-principles calculations we predict that periodically repeated junctions of armchair graphene nanoribbons of different widths form multiple quantum well structures. In these superlattice heterostructures the width as well as the energy-band gap is modulated in real space and specific states are confined in certain segments. Not only t...
Article
Full-text available
Using first-principles plane-wave calculations we predict that electronic and magnetic properties of graphene nanoribbons can be modified by the defect-induced itinerant states. Structure optimization gives rise to sig-nificant reconstruction of atomic structure, which is in good agreement with transmission electron microscope images. The band gaps...
Article
Full-text available
Using first-principles plane wave calculations we predict that electronic and magnetic properties of graphene nanoribbons can be affected by defect-induced itinerant states. The band gaps of armchair nanoribbons can be modified by hydrogen saturated holes. Defects due to periodically repeating vacancy or divacancies induce metallization, as well as...
Article
Full-text available
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...
Article
Full-text available
In this paper, we theoretically studied the electronic and magnetic properties of graphene and graphene nanoribbons functionalized by 3d transition-metal (TM) atoms. The binding energies and electronic and magnetic properties were investigated for the cases where TM atoms adsorbed to a single side and double sides of graphene. We found that 3d TM a...
Article
Based on first-principles calculations we predict that periodically repeated junctions of graphene ribbons of different widths form multiple quantum well structures having confined states. These quantum structures are unique, since both constituents of heterostructures are of the same material. The width as well as the bad gap, even the magnetic gr...
Article
Full-text available
Recently, first-principles calculations based on the spin-dependent density functional theory (DFT) have revealed that the magnetic ground state of a finite linear carbon chain capped by two transition metal (TM) atoms alternates between ferromagnetic and antiferromagnetic configurations depending on the number of carbon atoms. The character of ind...
Article
Full-text available
Dynamics of dissipation local vibrations to the surrounding substrate is a key issue in friction between sliding surfaces as well as in boundary lubrication. We consider a model system consisting of an excited nano-particle which is weakly coupled with a substrate. Using three different methods, we solve the dynamics of energy dissipation for diffe...
Article
Dynamics of dissipation of a local phonon distribution to the bulk is a key issue in boundary lubrication and friction between sliding surfaces. We consider a highly excited molecule which interacts weakly with the substrate surface. We study different types of coupling and substrates having different types of dimensionality and phonon densities of...
Article
Full-text available
In this paper we present an extensive study of the electronic, magnetic, and transport properties of finite and infinite periodic atomic chains composed of carbon atoms and 3d transition metal TM atoms using first-principles methods. Finite-size, linear molecules made of carbon atomic chains caped with TM atoms, i.e., TM-C n -TM structures are stab...