TY  - JOUR
AU  - Márk, Géza István
AU  - Vancsó, Péter
TI  - Ab-initio wave packet dynamical simulation of defects in 2D materials
JF  - PROCEEDINGS
J2  - PROCEEDINGS
VL  - 2020
PY  - 2020
IS  - 4
PG  - 7
SN  - 2504-3900
DO  - 10.3390/ASEC2020-07760
UR  - https://m2.mtmt.hu/api/publication/31670809
ID  - 31670809
LA  - English
DB  - MTMT
ER  - 

TY  - JOUR
AU  - Demin, V. A.
AU  - Kvashnin, D. G.
AU  - Vancsó, Péter
AU  - Márk, Géza István
AU  - Chernozatonskii, L. A.
TI  - Wave-Packet Dynamics Study of the Transport Characteristics of Perforated Bilayer Graphene Nanoribbons
JF  - JETP LETTERS
J2  - JETP LETT+
VL  - 112
PY  - 2020
IS  - 5
SP  - 305
EP  - 309
PG  - 5
SN  - 0021-3640
DO  - 10.1134/S0021364020170063
UR  - https://m2.mtmt.hu/api/publication/31670541
ID  - 31670541
AB  - The electrical conduction characteristics of perforated bilayer graphene nanoribbons are studied by the wave-packet dynamics method. The transport characteristics for typical examples of such nanostructures, which depend on the specific features of the contacts between the electrodes and the nanostructure under study, are estimated within a theoretical model. The effect of nanopores on the propagation of a wave packet across bilayer nanoribbons having two different configurations is revealed. These studies may become the first necessary prerequisite for the possible applications of such objects as components of electronic and optoelectronic circuits.
LA  - English
DB  - MTMT
ER  - 

TY  - JOUR
AU  - Pető, János
AU  - Ollár, Tamás
AU  - Vancsó, Péter
AU  - Popov, Z.I.
AU  - Magda, Gábor Zsolt
AU  - Dobrik, Gergely
AU  - Hwang, C.
AU  - Sorokin, P.B.
AU  - Tapasztó, Levente
TI  - Spontaneous doping of the basal plane of MoS2 single layers through oxygen substitution under ambient conditions
JF  - NATURE CHEMISTRY
J2  - NAT CHEM
VL  - 10
PY  - 2018
IS  - 12
SP  - 1246
EP  - 1251
PG  - 6
SN  - 1755-4330
DO  - 10.1038/s41557-018-0136-2
UR  - https://m2.mtmt.hu/api/publication/30331608
ID  - 30331608
LA  - English
DB  - MTMT
ER  - 

TY  - JOUR
AU  - Fülöp, Bálint
AU  - Tajkov, Zoltán
AU  - Pető, János
AU  - Kun, Péter
AU  - Koltai, János
AU  - Oroszlány, László
AU  - Tóvári, Endre
AU  - Murakawa, H
AU  - Tokura, Y
AU  - Bordács, Sándor
AU  - Tapasztó, Levente
AU  - Csonka, Szabolcs
TI  - Exfoliation of single layer BiTeI flakes
JF  - 2D MATERIALS
J2  - 2D MATER
VL  - 5
ET  - 0
PY  - 2018
IS  - 3
PG  - 9
SN  - 2053-1583
DO  - 10.1088/2053-1583/aac652
UR  - https://m2.mtmt.hu/api/publication/3390771
ID  - 3390771
N1  - Department of Physics, Budapest University of Technology and Economics, Budafoki út 8, Budapest, 1111, Hungary            
            MTA-BME Condensed Matter Research Group, Budafoki út 8, Budapest, 1111, Hungary            
            Department of Biological Physics, Eötvös Loránd University, Budapest, Hungary            
            Centre for Energy Research, Institute of Technical Physics and Materials Science, 2D Nanoelectronics Lendület Research Group, Budapest, Hungary            
            Department of Physics of Complex Systems, Eötvös Loránd University, Budapest, Hungary            
            MTA-BME Lendület Nanoelectronics Research Group, Budafoki út 8, Budapest, 1111, Hungary            
            Department of Physics, Osaka University, Toyonaka, 560-0043, Japan            
            Department of Applied Physics, University of Tokyo, Tokyo, 113-8656, Japan            
            RIKEN Center for Emergent Matter Science (CEMS), Wako, 351-0198, Japan
AB  - Spin orbit interaction is strongly enhanced in structures where a heavy element is embedded in an inversion asymmetric crystal field. A simple way for realizing such a setup is to take a single atomic layer of a heavy element and encapsulate it between two atomic layers of different elemental composition. BiTeI is a promising candidate for such a 2D crystal. In its bulk form BiTeI consists of loosely coupled three atom thick layers where a layer of high atomic number Bi are sandwiched between Te and I sheets. Despite considerable recent attention to bulk BiTeI due to its giant Rashba spin splitting, the isolation of a single layer remained elusive. In this work we report the first successful isolation and characterization of a single layer of BiTeI using a novel exfoliation technique on stripped gold. Our scanning probe studies and first principles calculations show that the fabricated 100 mu m sized BiTeI flakes are stable at ambient conditions. Giant Rashba splitting and spin-momentum locking of this new 2D crystal opens the way towards novel spintronic applications and synthetic topological heterostructures.
LA  - English
DB  - MTMT
ER  - 

TY  - JOUR
AU  - Márk, Géza István
AU  - Fejer, GR
AU  - Vancsó, Péter
AU  - Lambin, P
AU  - Biró, László Péter
TI  - Electronic Dynamics in Graphene and MoS2 Systems
JF  - PHYSICA STATUS SOLIDI B-BASIC RESEARCH
J2  - PHYS STAT SOL B BASIC RES
VL  - 254
PY  - 2017
IS  - 11
PG  - 5
SN  - 0370-1972
DO  - 10.1002/pssb.201700179
UR  - https://m2.mtmt.hu/api/publication/3327507
ID  - 3327507
AB  - We performed wave packet dynamical calculations for graphene-and MoS2 monolayers by a new formulation of the split-operator FFT method utilizing ab initio band structure results into the kinetic energy operator. While the time dependent dynamics is available through the solution of the time dependent Schrodinger equation in wave packet dynamics, the energy dependent dynamics is calculated by the application of the time-energy Fourier transform to the wave function. Time dependent probability results show an anisotropic spreading of the probability density current. The magnitude and angular dependence of the anisotropy is dependent (i) on the process creating the initial wave packet (e.g., injection from an STM tip or scattering on an impurity) and (ii) on the details of the band structure.
LA  - English
DB  - MTMT
ER  - 

TY  - JOUR
AU  - Pálinkás, András
AU  - Molnár, György
AU  - Magda, Gábor Zsolt
AU  - Hwang, Chanyong
AU  - Tapasztó, Levente
AU  - Samuely, Peter
AU  - Szabó, Pavol
AU  - Osváth, Zoltán
TI  - Novel graphene/Sn and graphene/SnOx hybrid nanostructures: Induced superconductivity and band gaps revealed by scanning probe measurements
JF  - CARBON
J2  - CARBON
VL  - 124
PY  - 2017
SP  - 611
EP  - 617
PG  - 7
SN  - 0008-6223
DO  - 10.1016/j.carbon.2017.09.026
UR  - https://m2.mtmt.hu/api/publication/3266108
ID  - 3266108
AB  - Abstract The development of functional composite nanomaterials based on graphene and metal nanoparticles (NPs) is currently the subject of intense research interest. In this study we report the preparation of novel type of graphene/Sn and graphene/SnOx (1 ≤ x ≤ 2) hybrid nanostructures and their investigation by scanning probe methods. First, we prepare Sn NPs by evaporating 7–8 nm tin on highly oriented pyrolytic graphite substrates. Graphene/Sn nanostructures are obtained by transferring graphene on top of the tin NPs immediately after evaporation. We show by scanning tunnelling microscopy (STM) and spectroscopy (STS) that tin NPs reduce significantly the environmental p-type doping of graphene. Furthermore, we demonstrate by low-temperature STM and STS measurements that superconductivity is induced in graphene, either directly supported by Sn NPs or suspended between them. Additionally, we prepare SnOx NPs by annealing the evaporated tin at 500 °C. STS measurements performed on hybrid graphene/SnOx nanostructures reveal the electronic band gap of SnOx NPs. The results can open new avenues for the fabrication of novel hybrid superconducting nanomaterials with designed structures and morphologies.
LA  - English
DB  - MTMT
ER  - 

TY  - JOUR
AU  - Nemes Incze, Péter
AU  - Kukucska, Gergő
AU  - Koltai, János
AU  - Kürti, Jenő
AU  - Hwang, C
AU  - Tapasztó, Levente
AU  - Biró, László Péter
TI  - Preparing local strain patterns in graphene by atomic force microscope based indentation
JF  - SCIENTIFIC REPORTS
J2  - SCI REP
VL  - 7
PY  - 2017
IS  - 1
PG  - 7
SN  - 2045-2322
DO  - 10.1038/s41598-017-03332-5
UR  - https://m2.mtmt.hu/api/publication/3253435
ID  - 3253435
AB  - Patterning graphene into various mesoscopic devices such as nanoribbons, quantum dots, etc. by lithographic techniques has enabled the guiding and manipulation of graphene's Dirac-type charge carriers. Graphene, with well-defined strain patterns, holds promise of similarly rich physics while avoiding the problems created by the hard to control edge configuration of lithographically prepared devices. To engineer the properties of graphene via mechanical deformation, versatile new techniques are needed to pattern strain profiles in a controlled manner. Here we present a process by which strain can be created in substrate supported graphene layers. Our atomic force microscope-based technique opens up new possibilities in tailoring the properties of graphene using mechanical strain.
LA  - English
DB  - MTMT
ER  - 

TY  - JOUR
AU  - Vancsó, Péter
AU  - Hagymási, Imre
AU  - Tapasztó, Levente
TI  - A magnetic phase-transition graphene transistor with tunable spin polarization
JF  - 2D MATERIALS
J2  - 2D MATER
VL  - 4
PY  - 2017
IS  - 2
PG  - 16
SN  - 2053-1583
DO  - 10.1088/2053-1583/aa5f2d
UR  - https://m2.mtmt.hu/api/publication/3205234
ID  - 3205234
AB  - Graphene nanoribbons (GNRs) have been proposed as potential building blocks for field effect transistor (FET) devices due to their quantum confinement bandgap. Here, we propose a novel GNR device concept, enabling the control of both charge and spin signals, integrated within the simplest three-terminal device configuration. In a conventional FET device, a gate electrode is employed to tune the Fermi level of the system in and out of a static bandgap. By contrast, in the switching mechanism proposed here, the applied gate voltage can dynamically open and close an interaction gap, with only a minor shift of the Fermi level. Furthermore, the strong interplay of the band structure and edge spin configuration in zigzag ribbons enables such transistors to carry spin polarized current without employing an external magnetic field or ferromagnetic contacts. Using an experimentally validated theoretical model, we show that such transistors can switch at low voltages and high speed, and the spin polarization of the current can be tuned from 0% to 50% by using the same back gate electrode. Furthermore, such devices are expected to be robust against edge irregularities and can operate at room temperature. Controlling both charge and spin signal within the simplest FET device configuration could open up new routes in data processing with graphene based devices.
LA  - English
DB  - MTMT
ER  - 

TY  - JOUR
AU  - Vancsó, Péter
AU  - Magda, Gábor Zsolt
AU  - Pető, János
AU  - Noh, JY
AU  - Kim, YS
AU  - Hwang, C
AU  - Biró, László Péter
AU  - Tapasztó, Levente
TI  - The intrinsic defect structure of exfoliated MoS2 single layers revealed by Scanning Tunneling Microscopy
JF  - SCIENTIFIC REPORTS
J2  - SCI REP
VL  - 6
PY  - 2016
PG  - 7
SN  - 2045-2322
DO  - 10.1038/srep29726
UR  - https://m2.mtmt.hu/api/publication/3122457
ID  - 3122457
AB  - MoS2 single layers have recently emerged as strong competitors of graphene in electronic and optoelectronic device applications due to their intrinsic direct bandgap. However, transport measurements reveal the crucial role of defect-induced electronic states, pointing out the fundamental importance of characterizing their intrinsic defect structure. Transmission Electron Microscopy (TEM) is able to image atomic scale defects in MoS2 single layers, but the imaged defect structure is far from the one probed in the electronic devices, as the defect density and distribution are substantially altered during the TEM imaging. Here, we report that under special imaging conditions, STM measurements can fully resolve the native atomic scale defect structure of MoS2 single layers. Our STM investigations clearly resolve a high intrinsic concentration of individual sulfur atom vacancies, and experimentally identify the nature of the defect induced electronic mid-gap states, by combining topographic STM images with ab intio calculations. Experimental data on the intrinsic defect structure and the associated defect-bound electronic states that can be directly used for the interpretation of transport measurements are essential to fully understand the operation, reliability and performance limitations of realistic electronic devices based on MoS2 single layers.
LA  - English
DB  - MTMT
ER  - 

TY  - JOUR
AU  - Magda, Gábor Zsolt
AU  - Pető, János
AU  - Dobrik, Gergely
AU  - Hwang, C
AU  - Biró, László Péter
AU  - Tapasztó, Levente
TI  - Exfoliation of large-area transition metal chalcogenide single layers
JF  - SCIENTIFIC REPORTS
J2  - SCI REP
VL  - 5
PY  - 2015
PG  - 5
SN  - 2045-2322
DO  - 10.1038/srep14714
UR  - https://m2.mtmt.hu/api/publication/2984284
ID  - 2984284
AB  - Isolating large-areas of atomically thin transition metal chalcogenide crystals is an important but challenging task. The mechanical exfoliation technique can provide single layers of the highest structural quality, enabling to study their pristine properties and ultimate device performance. However, a major drawback of the technique is the low yield and small (typically <10 um) lateral size of the produced single layers. Here, we report a novel mechanical exfoliation technique, based on chemically enhanced adhesion, yielding MoS<inf>2</inf>single layers with typical lateral sizes of several hundreds of microns. The idea is to exploit the chemical affinity of the sulfur atoms that can bind more strongly to a gold surface than the neighboring layers of the bulk MoS<inf>2</inf> crystal. Moreover, we found that our exfoliation process is not specific to MoS<inf>2</inf>, but can be generally applied for various layered chalcogenides including selenites and tellurides, providing an easy access to large-area 2D crystals for the whole class of layered transition metal chalcogenides.
LA  - English
DB  - MTMT
ER  -