“Photovoltaic effect and evidence of carrier multiplication in graphene vertical homojunctions with asymmetrical metal contacts”. Chen JJ, Wang Q, Meng J, Ke X, Van Tendeloo G, Bie YQ, Liu J, Liu K, Liao ZM, Sun D, Yu D;, ACS nano 9, 8851 (2015). http://doi.org/10.1021/acsnano.5b02356
Abstract: Graphene exhibits exciting potentials for high-speed wideband photodetection and high quantum efficiency solar energy harvest because of its broad spectral absorption, fast photoelectric response, and potential carrier multiplication. Although photocurrent can be generated near a metalgraphene interface in lateral devices, the photoactive area is usually limited to a tiny one-dimensional line-like interface region. Here, we report photoelectric devices based on vertical graphene two-dimensional homojunction, which is fabricated via vertically stacking four graphene monolayers with asymmetric metal contacts. The devices show excellent photovoltaic output with excitation wavelength ranging from visible light to mid-infrared. The wavelength dependence of the internal quantum efficiency gives direct evidence of the carrier multiplication effect in graphene. The simple fabrication process, easy scale-up, large photoresponsive active area, and broadband response of the vertical graphene device are very promising for practical applications in optoelectronics and photovoltaics.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 13.942
Times cited: 11
DOI: 10.1021/acsnano.5b02356
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“PIC-MC simulation of an RF capacitively coupled Ar/H2 discharge”. Neyts E, Yan M, Bogaerts A, Gijbels R, Nuclear instruments and methods in physics research: B 202, 300 (2003). http://doi.org/10.1016/S0168-583X(02)01873-6
Keywords: A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 1.109
Times cited: 8
DOI: 10.1016/S0168-583X(02)01873-6
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“Piezoelectric surface acoustical phonon limited mobility of electrons in graphene on a GaAs substrate”. Zhang SH, Xu W, Badalyan SM, Peeters FM, Physical review : B : condensed matter and materials physics 87, 075443 (2013). http://doi.org/10.1103/PhysRevB.87.075443
Abstract: We study the mobility of Dirac fermions in monolayer graphene on a GaAs substrate, limited by the combined action of the extrinsic potential of piezoelectric surface acoustical phonons of GaAs (PA) and of the intrinsic deformation potential of acoustical phonons in graphene (DA). In the high-temperature (T) regime, the momentum relaxation rate exhibits the same linear dependence on T but different dependencies on the carrier density n, corresponding to the mobility mu proportional to 1 root n and 1/n, respectively for the PA and DA scattering mechanisms. In the low-T Bloch-Gruneisen regime, the mobility shows the same square-root density dependence mu proportional to root n, but different temperature dependencies mu proportional to T-3 and T-4, respectively for PA and DA phonon scattering. DOI: 10.1103/PhysRevB.87.075443
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 25
DOI: 10.1103/PhysRevB.87.075443
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“Plasmon and coupled plasmon-phonon modes in graphene in the presence of a driving electric field”. Zhao CX, Xu W, Dong HM, Peeters FM, Physical review : B : condensed matter and materials physics 89, 195447 (2014). http://doi.org/10.1103/PhysRevB.89.195447
Abstract: We present a theoretical study of the plasmon and coupled plasmon-phonon modes induced by intraband electron-electron interaction in graphene in the presence of driving dc electric field. We find that the electric field dependence of these collective excitation modes in graphene differs significantly from that in a conventional two-dimensional electron gas with a parabolic energy spectrum. This is due mainly to the fact that graphene has a linear energy spectrum and the Fermi velocity of electrons in graphene is much larger than the drift velocity of electrons. The obtained results demonstrate that the plasmon and coupled plasmon-phonon modes in graphene can be tuned by applying not only the gate voltage but also the source-to-drain field. The manipulation of plasmon and coupled plasmon-phonon modes by source-to-drain voltage can let graphene be more conveniently applied as an advanced plasmonic material.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 9
DOI: 10.1103/PhysRevB.89.195447
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“Plasmonic excitations in Coulomb-coupled N-layer graphene structures”. Zhu J-J, Badalyan SM, Peeters FM, Physical review : B : condensed matter and materials physics 87, 085401 (2013). http://doi.org/10.1103/PhysRevB.87.085401
Abstract: We study Dirac plasmons and their damping in spatially separated N-layer graphene structures at finite doping and temperatures. The plasmon spectrum consists of one optical excitation with square-root dispersion and N – 1 acoustical excitations with linear dispersion, which are undamped at zero temperature and finite doping within a triangular energy region outside the electron-hole continuum. In the long-wavelength limit the energy and weight of the optical plasmon modes increase, respectively, as the square root and linearly with N in agreement with recent experimental findings. The energy and weight of the upper-lying acoustical branches also increase with N. This increase is strongest for the uppermost acoustical mode, and we find that its energy can exceed at some value of momentum the plasmon energy in an individual graphene sheet. Meanwhile, the energy of the low-lying acoustical branches decreases weakly with N as compared with the single acoustical mode in double-layer graphene structures. Our numerical calculations provide a detailed understanding of the overall behavior of the wave-vector dependence of the optical and acoustical multilayer plasmon modes and show how their dispersion and damping are modified as a function of temperature, interlayer spacing, and inlayer carrier density in (un)balanced graphene multilayer structures. DOI: 10.1103/PhysRevB.87.085401
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 59
DOI: 10.1103/PhysRevB.87.085401
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“Polyethylene glycol conjugated polymeric nanocapsules for targeted delivery of quercetin to folate-expressing cancer cells in vitro and in vivo”. El-Gogary RI, Rubio N, Wang JTW, Al-Jamal WT, Bourgognon M, Kafa H, Naeem M, Klippstein R, Abbate V, Leroux F, Bals S, Van Tendeloo G, Kamel AO, Awad GAS, Mortada ND, Al-Jamal KT;, ACS nano 8, 1384 (2014). http://doi.org/10.1021/nn405155b
Abstract: In this work we describe the formulation and characterization of chemically modified polymeric nanocapsules incorporating the anticancer drug, quercetin, for the passive and active targeting to tumors. Folic acid was conjugated to poly(lactide-co-glycolide) (PLGA) polymer to facilitate active targeting to cancer cells. Two different methods for the conjugation of PLGA to folic acid were employed utilizing polyethylene glycol (PEG) as a spacer. Characterization of the conjugates was performed using FTIR and H-1 NMR studies. The PEG and folk acid content was independent of the conjugation methodology employed. PEGylation has shown to reduce the size of the nanocapsule; moreover, zeta-potential was shown to be polymer-type dependent. Comparative studies on the cytotoxicity and cellular uptake of the different formulations by He La cells, in the presence and absence of excess folic acid, were carried out using MTT assay and Confocal Laser Scanning Microscopy, respectively. Both results confirmed the selective uptake and cytotoxicity of the folic acid targeted nanocapsules to the folate enriched cancer cells in a folate-dependent manner. Finally, the passive tumor accumulation and the active targeting of the nanocapsules to folate-expressing cells were confirmed upon intravenous administration in He La or IGROV-1 tumor-bearing mice. The developed nanocapsules provide a system for targeted delivery of a range of hydrophobic anticancer drugs in vivo.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 13.942
Times cited: 144
DOI: 10.1021/nn405155b
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“Polyhedral iron oxide coreshell nanoparticles in a biodegradable polymeric matrix : preparation, characterization and application in magnetic particle hyperthermia and drug delivery”. Filippousi M, Altantzis T, Stefanou G, Betsiou M, Bikiaris DN, Angelakeris M, Pavlidou E, Zamboulis D, Van Tendeloo G, RSC advances 3, 24367 (2013). http://doi.org/10.1039/c3ra43747g
Abstract: Polyhedral magnetic iron oxide nanocrystals with multiple facets have been embedded in biocompatible and biodegradable polymeric matrices in order to study their structural, magnetic features and alternating-current (AC) magnetic heating efficiency. The encapsulation of iron oxide nanoparticles into a polymer matrix was confirmed by transmission electron microscopy and further corroborated by high angle annular dark field scanning transmission electron microscopy (HAADF-STEM). HAADF-STEM tomography proved that the iron oxide nanocrystals consist of well-defined polyhedral structures with multiple facets. The magnetic features were found to be in good agreement with the structural and morphological features and are maintained even after encapsulation. Furthermore, the magnetic nanoparticles inside these matrices may be considered as good candidates for biomedical applications in hyperthermia treatments because of their high heating capacity exhibited under an alternating magnetic field. The anticancer Taxol drug was encapsulated in these nanoparticles and its physical state and release rate at 37 and 42 °C was studied.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 3.108
Times cited: 19
DOI: 10.1039/c3ra43747g
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“Portlandite crystal : bulk, bilayer, and monolayer structures”. Aierken Y, Sahin H, Iyikanat F, Horzum S, Suslu A, Chen B, Senger RT, Tongay S, Peeters FM, Physical review : B : condensed matter and materials physics 91, 245413 (2015). http://doi.org/10.1103/PhysRevB.91.245413
Abstract: Ca(OH)(2) crystals, well known as portlandite, are grown in layered form, and we found that they can be exfoliated on different substrates. We performed first principles calculations to investigate the structural, electronic, vibrational, and mechanical properties of bulk, bilayer, and monolayer structures of this material. Different from other lamellar structures such as graphite and transition-metal dichalcogenides, intralayer bonding in Ca(OH)(2) is mainly ionic, while the interlayer interaction remains a weak dispersion-type force. Unlike well-known transition-metal dichalcogenides that exhibit an indirect-to-direct band gap crossover when going from bulk to a single layer, Ca(OH)(2) is a direct band gap semiconductor independent of the number layers. The in-plane Young's modulus and the in-plane shear modulus of monolayer Ca(OH)(2) are predicted to be quite low while the in-plane Poisson ratio is larger in comparison to those in the monolayer of ionic crystal BN. We measured the Raman spectrum of bulk Ca(OH)(2) and identified the high-frequency OH stretching mode A(1g) at 3620 cm(-1). In this study, bilayer and monolayer portlandite [Ca(OH)(2)] are predicted to be stable and their characteristics are analyzed in detail. Our results can guide further research on ultrathin hydroxites.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 29
DOI: 10.1103/PhysRevB.91.245413
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“Post-synthesis deposition of V-Zeolitic nanoparticles in SBA-15”. Meynen V, Beyers E, Cool P, Vansant EF, Mertens M, Weyten H, Lebedev OI, Van Tendeloo G, Chemical communications , 898 (2004). http://doi.org/10.1039/b400636d
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT); Laboratory of adsorption and catalysis (LADCA)
Impact Factor: 6.319
Times cited: 22
DOI: 10.1039/b400636d
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“Predicted field-dependent increase of critical currents in asymmetric superconducting nanocircuits”. Clem JR, Mawatari Y, Berdiyorov GR, Peeters FM, Physical review : B : condensed matter and materials physics 85, 144511 (2012). http://doi.org/10.1103/PhysRevB.85.144511
Abstract: The critical current of a thin superconducting strip of width W much larger than the Ginzburg-Landau coherence length xi but much smaller than the Pearl length Lambda = 2 lambda(2)/d is maximized when the strip is straight with defect-free edges. When a perpendicular magnetic field is applied to a long straight strip, the critical current initially decreases linearly with H but then decreases more slowly with H when vortices or antivortices are forced into the strip. However, in a superconducting strip containing sharp 90 degrees or 180 degrees turns, the zero-field critical current at H = 0 is reduced because vortices or antivortices are preferentially nucleated at the inner corners of the turns, where current crowding occurs. Using both analytic London-model calculations and time-dependent Ginzburg-Landau simulations, we predict that in such asymmetric strips the resulting critical current can be increased by applying a perpendicular magnetic field that induces a current-density contribution opposing the applied current density at the inner corners. This effect should apply to all turns that bend in the same direction.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 40
DOI: 10.1103/PhysRevB.85.144511
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“Production and structure of exfoliated graphite/coke composites modified by ZrO2 nanoparticles”. Afanasov IM, Van Tendeloo G, Mateev AT, New carbon materials 25, 255 (2010). http://doi.org/10.1016/S1872-5805(09)60032-9
Abstract: Exfoliated graphite/coke composites modified by ZrO2 nanoparticles were produced using two different techniques and characterized by means of X-ray diffraction, scanning and transmission electron microscopy. In the first, low-density exfoliated graphite/coke blocks were dipped repeatedly and alternately in ZrO(NO3)2 and NH4OH solutions and subsequently heat treated at 1200°C in nitrogen to deposit thin layers of ZrO2 nanoparticles on the free surfaces of the carbon matrix. In the second, a mixture of expandable graphite, phenol-formaldehyde resin powder, and ZrOC2O4-modified fibrous cellulose in a sealed container was submitted to thermal shock at 900 °C followed by heat treatment at 1 200 °C in nitrogen to obtain the modified composites. The ZrO2 nanoparticles formed in the second technique were incorporated into the composites in three length scales: 6-30 nm-isolated nanoparticles and small blobs, 200-1000 nm-lengthy dendrite-like structures, and thin layer adhering to the surface of the 1-40 μm long cellulose carbon fibers.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
DOI: 10.1016/S1872-5805(09)60032-9
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“Proximity-induced pseudogap in mesoscopic superconductor/normal-metal bilayers”. Zha G-Q, Covaci L, Zhou S-P, Peeters FM, Physical review : B : condensed matter and materials physics 82, 140502 (2010). http://doi.org/10.1103/PhysRevB.82.140502
Abstract: Recent scanning tunneling microscopy (STM) measurements of the proximity effect in Au/La2−xSrxCuO4 and La1.55Sr0.45CuO4/La2−xSrxCuO4 bilayers showed a proximity-induced pseudogap [O. Yuli, I. Asulin, Y. Kalcheim, G. Koren, and O. Millo, Phys. Rev. Lett. 103, 197003 (2009)]. We describe the proximity effect in mesoscopic superconductor/normal-metal bilayers by using the Bogoliubov-de Gennes equations for a tight-binding Hamiltonian with competing antiferromagnetic and d-wave superconductivity orders. The temperature-dependent local density of states is calculated as a function of the distance from the interface. Bound state due to both d-wave and spin-density wave gaps are formed in the normal metal for energies less than the respective gaps. If there is a mismatch between the Fermi velocities in the two layers we observe that these states will shift in energy when spin-density wave order is present, thus inducing a minigap at finite energy. We conclude that the STM measurement in the proximity structures is able to distinguish between the two scenarios proposed for the pseudogap (competing or precursor to superconductivity).
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 7
DOI: 10.1103/PhysRevB.82.140502
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“The quantized Hall effect in pulsed magnetic fields”. van der Burgt M, Thoen P, Herlach F, Peeters FM, Harris JJ, Foxon CT, Physica: B 177, 409 (1992). http://doi.org/10.1016/0921-4526(92)90139-J
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 1.319
Times cited: 14
DOI: 10.1016/0921-4526(92)90139-J
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“Quantum cutting in Li (770 nm) and Yb (1000 nm) co-dopant emission bands by energy transfer from the ZnO nano-crystalline host”. Shestakov MV, Tikhomirov VK, Kirilenko D, Kuznetsov AS, Chibotaru LF, Baranov AN, Van Tendeloo G, Moshchalkov VV, Optics express 19, 15955 (2011). http://doi.org/10.1364/OE.19.015955
Abstract: Li-Yb co-doped nano-crystalline ZnO has been synthesized by a method of thermal growth from the salt mixtures. X-ray diffraction, transmission electron microscopy, atomic absorption spectroscopy and optical spectroscopy confirm the doping and indicate that the dopants may form Li-Li and Yb3+-Li based nanoclusters. When pumped into the conduction and exciton absorption bands of ZnO between 250 to 425 nm, broad emission bands of about 100 nm half-height-width are excited around 770 and 1000 nm, due to Li and Yb dopants, respectively. These emission bands are activated by energy transfer from the ZnO host mostly by quantum cutting processes, which generate pairs of quanta in Li (770 nm) and Yb (1000 nm) emission bands, respectively, out of one quantum absorbed by the ZnO host. These quantum cutting phenomena have great potential for application in the down-conversion layers coupled to the Si solar cells.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 3.307
Times cited: 19
DOI: 10.1364/OE.19.015955
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“Real-space simulations of spin-polarized electronic transitions in iron”. Schattschneider P, Verbeeck J, Mauchamp V, Jaouen M, Hamon A-L, Physical review : B : condensed matter and materials physics 82, 144418 (2010). http://doi.org/10.1103/PhysRevB.82.144418
Abstract: After the advent of energy-loss magnetic chiral dichroism (EMCD) in 2006, rapid progress in theoretical understanding and in experimental performance was achieved, recently demonstrating a spatial resolution of better than 2 nm. Similar to the x-ray magnetic circular dichroism technique, EMCD is used to study atom specific magnetic moments. The latest generation of electron microscopes opens the road to the mapping of spin moments on the atomic scale with this method. Here the theoretical background to reach this challenging aim is elaborated. Numerical simulations of the L3 transition in an Fe specimen, based on a combination of the density-matrix approach for inelastic electron scattering with the propagation of the probe electron in the lattice potential indicate the feasibility of single spin mapping in the electron microscope.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 3.836
Times cited: 11
DOI: 10.1103/PhysRevB.82.144418
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“Relaxor ferroelectricity and magnetoelectric coupling in ZnOCo nanocomposite thin films : beyond multiferroic composites”. Li DY, Zeng YJ, Batuk D, Pereira LMC, Ye ZZ, Fleischmann C, Menghini M, Nikitenko S, Hadermann J, Temst K, Vantomme A, Van Bael MJ, Locquet JP, Van Haesendonck C;, ACS applied materials and interfaces 6, 4737 (2014). http://doi.org/10.1021/am4053877
Abstract: ZnOCo nanocomposite thin films are synthesized by combination of pulsed laser deposition of ZnO and Co ion implantation. Both superparamagnetism and relaxor ferroelectricity as well as magnetoelectric coupling in the nanocomposites have been demonstrated. The unexpected relaxor ferroelectricity is believed to be the result of the local lattice distortion induced by the incorporation of the Co nanoparticles. Magnetoelectric coupling can be attributed to the interaction between the electric dipole moments and the magnetic moments, which are both induced by the incorporation of Co. The introduced ZnOCo nanocomposite thin films are different from conventional strain-mediated multiferroic composites.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 7.504
Times cited: 21
DOI: 10.1021/am4053877
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“Remote electron plasmon polaron in graphene”. Krstajić, PM, Peeters FM, Physical review : B : condensed matter and materials physics 85, 085436 (2012). http://doi.org/10.1103/PhysRevB.85.085436
Abstract: The Coulomb interaction and the correlation of a remote electron with a single layer of graphene is investigated in the presence of a magnetic field applied perpendicular to the graphene layer. The remote electron polarizes the electron gas in the graphene layer, which we describe in terms of excitations of virtual plasmons in graphene. The composite quasiparticle formed by electron plus polarization is called a plasmon polaron. The ground-state energy of this quasiparticle is calculated within perturbation theory for remote electrons in different environments.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 4
DOI: 10.1103/PhysRevB.85.085436
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“Reply to “Comment on 'Vortices induced in a superconducting loop by asymmetric kinetic inductance and their detection in transport measurements' ””. Berdiyorov GR, Milošević, MV, Peeters FM, Physical review : B : condensed matter and materials physics 90, 056502 (2014). http://doi.org/10.1103/PhysRevB.90.056502
Abstract: Our calculations, within known limitations of Ginzburg-Landau theory, are fully correct and valid for transport phenomena in asymmetric mesoscopic superconductors, deep in the superconducting state. We deemed the experiments of Burlakov et al. [JETP Lett. 86, 517 (2007)] relevant and important to mention in the general context of our paper since the observed shifts in the oscillations of different quantities are qualitatively similar, even though those measurements are performed close to the superconducting-normal state transition in the so-called Little-Parks regime.
Keywords: Editorial; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 1
DOI: 10.1103/PhysRevB.90.056502
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“Resonant harmonic generation and collective spin rotations in electrically driven quantum dots”. Nowak MP, Szafran B, Peeters FM, Physical review : B : condensed matter and materials physics 86, 125428 (2012). http://doi.org/10.1103/PhysRevB.86.125428
Abstract: Spin rotations induced by an ac electric field in a two-electron double quantum dot are studied by an exact numerical solution of the time-dependent Schrodinger equation in the context of recent electric-dipole spin resonance experiments on gated nanowires. We demonstrate that the splitting of the main resonance line by the spin exchange coupling is accompanied by the appearance of fractional resonances and that both these effects are triggered by interdot tunnel coupling. We find that the ac-driven system generates residual but distinct harmonics of the driving frequency, which are amplified when tuned to the main transition frequency. The mechanism is universal for electron systems in electrically driven potentials and works also in the absence of electron-electron interaction or spin-orbit coupling.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 29
DOI: 10.1103/PhysRevB.86.125428
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“Resonant magnetopolaron coupling to both polar and neutral optical phonons in the layer compound InSe”. Peeters FM, Wu XG, Devreese JT, Watts M, Nicholas RJ, Howell DF, van Bockstal L, Herlach F, Langerak CJGM, Singleton J, Chevy A, Surface science 263, 654 (1992). http://doi.org/10.1016/0039-6028(92)90429-A
Keywords: A1 Journal article; Condensed Matter Theory (CMT); Theory of quantum systems and complex systems
Impact Factor: 1.925
Times cited: 4
DOI: 10.1016/0039-6028(92)90429-A
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“Resonant tunneling and localized states in a graphene monolayer with a mass gap”. Zalipaev V, Linton CM, Croitoru MD, Vagov A, Physical review : B : condensed matter and materials physics 91, 085405 (2015). http://doi.org/10.1103/PhysRevB.91.085405
Abstract: We study tunneling of quasiparticles through potential barriers in a graphene monolayer with the mass gap using a semiclassical (WKB) approach. The main equations are derived in away similar to the WKB theory for the Schrodinger equation, which allows for explicit solutions at all orders. The analog of the classical action is used to distinguish types of possible stationary states in the system. The analysis focuses on the resonant scattering and the hole states localized in the vicinity of a barrier that are often overlooked. The scattering coefficients for the physically interesting limits are obtained by matching the WKB approximation with the known solutions at turning points. The localized states demonstrate unconventional properties and lead to alterations of the single particle density of states.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 3
DOI: 10.1103/PhysRevB.91.085405
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“Resonant valley filtering of massive Dirac electrons”. Moldovan D, Masir MR, Covaci L, Peeters FM, Physical review : B : condensed matter and materials physics 86, 115431 (2012). http://doi.org/10.1103/PhysRevB.86.115431
Abstract: Electrons in graphene, in addition to their spin, have two pseudospin degrees of freedom: sublattice and valley pseudospin. Valleytronics uses the valley degree of freedom as a carrier of information similarly to the way spintronics uses electron spin. We show how a double-barrier structure consisting of electric and vector potentials can be used to filter massive Dirac electrons based on their valley index. We study the resonant transmission through a finite number of barriers and we obtain the energy spectrum of a superlattice consisting of electric and vector potentials. When a mass term is included, the energy bands and energy gaps at the K and K′ points are different and they can be tuned by changing the potential.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 55
DOI: 10.1103/PhysRevB.86.115431
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“Review of phonon behaviour and microstructural development leading to martensitic transformations in NixAl100-x alloys”. Tanner LE, Shapiro SM, Schryvers D, Noda Y, Shape memory materials and phenomena: fundamental aspects and applications 246, 265 (1992)
Keywords: A3 Journal article; Electron microscopy for materials research (EMAT)
Times cited: 4
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“Role of atomic vacancies and boundary conditions on ballistic thermal transport in graphene nanoribbons”. Scuracchio P, Costamagna, Peeters FM, Dobry A, Physical review : B : condensed matter and materials physics 90, 035429 (2014). http://doi.org/10.1103/PhysRevB.90.035429
Abstract: Quantum thermal transport in armchair and zigzag graphene nanoribbons is investigated in the presence of single atomic vacancies and subject to different boundary conditions. We start with a full comparison of the phonon polarizations and energy dispersions as given by a fifth-nearest-neighbor force-constant model (5NNFCM) and by elasticity theory of continuum membranes (ETCM). For free-edge ribbons, we discuss the behavior of an additional acoustic edge-localized flexural mode, known as fourth acoustic branch (4ZA), which has a small gap when it is obtained by the 5NNFCM. Then, we show that ribbons with supported edges have a sample-size dependent energy gap in the phonon spectrum which is particularly large for in-plane modes. Irrespective to the calculation method and the boundary condition, the dependence of the energy gap for the low-energy optical phonon modes against the ribbon width W is found to be proportional to 1/W for in-plane, and 1/W-2 for out-of-plane phonon modes. Using the 5NNFCM, the ballistic thermal conductance and its contributions from every single phonon mode are then obtained by the nonequilibrium Green's function technique. We found that, while edge and central localized single atomic vacancies do not affect the low-energy transmission function of in-plane phonon modes, they reduce considerably the contributions of the flexural modes. On the other hand, in-plane modes contributions are strongly dependent on the boundary conditions and at low temperatures can be highly reduced in supported-edge samples. These findings could open a route to engineer graphene based devices where it is possible to discriminate the relative contribution of polarized phonons and to tune the thermal transport on the nanoscale.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 20
DOI: 10.1103/PhysRevB.90.035429
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“Role of carbon and nitrogen in Fe2C and Fe2N from first-principles calculations”. Fang CM, van Huis MA, Jansen J, Zandbergen HW, Physical review : B : condensed matter and materials physics 84, 094102 (2011). http://doi.org/10.1103/PhysRevB.84.094102
Abstract: Although Fe2C and Fe2N are technologically important materials, the exact nature of the chemical bonding of C and N atoms and the related impact on the electronic properties are at present unclear. Here, results of first-principles electronic structure calculations for Fe2X (X = C, N) phases are presented. The electronic structure calculations show that the roles of N and C in iron nitrides and carbides are comparable, and that the X-X interactions have significant impact on electronic properties. Accurate analysis of the spatially resolved differences in electron densities reveals a subtle distinction between the chemical bonding and charge transfer of N and C ions.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 3.836
Times cited: 24
DOI: 10.1103/PhysRevB.84.094102
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“Ruthenocene and cyclopentadienyl pyrrolyl ruthenium as precursors for ruthenium atomic layer deposition : a comparative study of dissociation enthalpies”. Phung QM, Vancoillie S, Delabie A, Pourtois G, Pierloot K, Theoretical chemistry accounts : theory, computation, and modeling 131, 1238 (2012). http://doi.org/10.1007/s00214-012-1238-3
Abstract: RuCp2 (ruthenocene) and RuCpPy (cyclopentadienyl pyrrolyl ruthenium) complexes are used in ruthenium (Ru) atomic layer deposition (ALD) but exhibit a markedly different reactivity with respect to the substrate and co-reactant. In search of an explanation, we report here the results of a comparative study of the heterolytic and homolytic dissociation enthalpy of these two ruthenium complexes, making use of either density functional theory (DFT) or multiconfigurational perturbation theory (CASPT2). While both methods predict distinctly different absolute dissociation enthalpies, they agree on the relative values between both molecules. A reduced heterolytic dissociation enthalpy is obtained for RuCpPy compared to RuCp2, although the difference obtained from CASPT2 (19.9 kcal/mol) is slightly larger than the one obtained with any of the DFT functionals (around 17 kcal/mol). Both methods also agree on the more pronounced stability of the Cp- ligand in RuCpPy than in RuCp2 (by around 9 kcal/mol with DFT and by 6 kcal/mol with CASPT2).
Keywords: A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 1.89
Times cited: 5
DOI: 10.1007/s00214-012-1238-3
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“Scattering of ballistic electrons at a mesoscopic spot of strong magnetic field”. Novoselov KS, Geim AK, Dubonos SV, Cornelissens YG, Peeters FM, Maan JC, Physical review : B : condensed matter and materials physics 65, 233312 (2002). http://doi.org/10.1103/PhysRevB.65.233312
Abstract: We report quenching of the Hall effect with increasing magnetic field confined in a micron-sized spot. Such fields were created by placing tall ferromagnetic pillars on top of a two-dimensional electron gas, which allowed us to achieve the field strength up to 0.4 T under the pillars in the absence of external field. The quenching is accompanied by an anomalous increase in resistance and occurs when the cyclotron diameter matches the size of the magnetic spot. The results are explained by a rapid increase in the number of electrons that are scattered or quasilocalized by the magnetic region.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 38
DOI: 10.1103/PhysRevB.65.233312
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“Scattering of Dirac electrons by circular mass barriers : valley filter and resonant scattering”. Masir MR, Matulis A, Peeters FM, Physical review : B : condensed matter and materials physics 84, 245413 (2011). http://doi.org/10.1103/PhysRevB.84.245413
Abstract: The scattering of two-dimensional (2D) massless Dirac electrons is investigated in the presence of a random array of circular mass barriers. The inverse momentum relaxation time and the Hall factor are calculated and used to obtain parallel and perpendicular resistivity components within linear transport theory. We found a nonzero perpendicular resistivity component which has opposite sign for electrons in the different K and K′ valleys. This property can be used for valley filter purposes. The total cross section for scattering on penetrable barriers exhibits resonances due to the presence of quasibound states in the barriers that show up as sharp gaps in the cross section while for Schrödinger electrons they appear as peaks.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 32
DOI: 10.1103/PhysRevB.84.245413
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“Second-order multiple-quanta flux entry into a perforated spherical mesoscopic superconductor”. Xu B, Milošević, MV, Peeters FM, Physical review : B : condensed matter and materials physics 82, 214501 (2010). http://doi.org/10.1103/PhysRevB.82.214501
Abstract: Flux entry in type-II superconductors without prominent symmetry is a first-order phase transition, where flux enters conventionally gradual in units of a flux quantum. Here we show that neither is necessarily the case in a mesoscopic superconducting sphere with a perforation. In axially applied magnetic field, vortices initially occupy the hole, and can oppose further flux entry in the sample. As a result, multiple-quanta flux entry is found at significantly higher field, and it can manifest as a second-order transition due to suppressed geometric barrier at the equatorial belt of the sample. At high fields a new state is found, with gradually destroyed condensate from the equator inwards, the exact opposite of surface superconductivity.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 2
DOI: 10.1103/PhysRevB.82.214501
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“Selective decoration of isolated carbon nanotubes by potassium evaporation : scanning photoemission microscopy and density functional theory”. Struzzi C, Erbahar D, Scardamaglia M, Amati M, Gregoratti L, Lagos, Van Tendeloo G, Snyders R, Ewels C, Bittencourt C, Journal of materials chemistry C : materials for optical and electronic devices 3, 2518 (2015). http://doi.org/10.1039/c4tc02478h
Abstract: Site selective doping of aligned carbon nanostructures represents a promising approach for their implementation in actual devices. In the present work we report on alkali metals decoration on low density vertically aligned carbon nanotubes, disclosing the possibility of engineering site selective depositions of potassium atoms on the carbon systems. Photoemission measurements were combined with microscopy demonstrating the effective spatial control of alkali deposition. The changes of electronic structures of locally doped carbon regions were studied by exploiting the ability of the scanning photoemission microscopy technique. From the analysis of experimental data supported by theoretical calculations, we show the tuning of the charge transfer from potassium to carbon atoms belonging to neighboring nanotubes or along the same tube structure.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 5.256
Times cited: 6
DOI: 10.1039/c4tc02478h
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