| 1. |
- Apell, Peter, 1952, et al.
(författare)
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Edge plasmons in graphene nanostructures
- 2011
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Ingår i: Physical Review B - Condensed Matter and Materials Physics. - 2469-9950 .- 2469-9969. ; 84:8
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Tidskriftsartikel (refereegranskat)abstract
- Plasmon modes in graphene are influenced by the unusual dispersion relation of the material. For bulk plasmons this results in a n(1/4) dependence of the plasma frequency on the charge density, as opposed to the n(1/2) dependence in two-dimensional electron gas (2DEG); yet, bulk plasmon dispersion in graphene follows a similar q(1/2) behavior as for other two-dimensional materials. In this work we consider finite graphene nanostructures, semi-infinite sheets, and circular disks and study edge plasmons that are confined to the boundaries of the structures. We find that, for abrupt edges, graphene edge plasmons behave analogously to those in 2DEGs, but, for gradual edge profiles, important distinctions arise. In particular, we show that for a linear edge profile, graphene supports fewer edge modes than a 2DEG at a given q, and the edge monopole plasmon dispersion in graphene follows a q(1/4) law in contrast to the q(0) behavior seen in 2DEGs. RAMOWITZ M, 1964
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| 2. |
- Atalaya, Juan, 1981, et al.
(författare)
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Continuum elastic modeling of graphene resonators
- 2008
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Ingår i: Nano Letters. - 1530-6992 .- 1530-6984. ; 8:12, s. 4196-4200
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Tidskriftsartikel (refereegranskat)abstract
- Starting from an atomistic approach, we have derived a hierarchy of successively more simplified continuum elasticity descriptions for modeling the mechanical properties of suspended graphene sheets. We find that already for deflections of the order of 0.5 Å a theory that correctly accounts for nonlinearities is necessary and that for many purposes a set of coupled Duffing-type equations may be used to accurately describe the dynamics of graphene membranes. The descriptions are validated by applying them to square graphene-based resonators with clamped edges and studying numerically their mechanical responses. Both static and dynamic responses are treated, and we find good agreement with recent experimental findings.
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| 3. |
- Atalaya, Juan, 1981, et al.
(författare)
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Elasticity theory for graphene membranes
- 2010
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Ingår i: Adsorption and Phase Behaviour in Nanochannels and Nanotubes. - Dordrecht : Springer Netherlands. - 9789048124800 ; , s. 273-290
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- Starting from an atomistic approach we have derived a hierarchy of successively more simplified continuum elasticity descriptions for modeling the mechanical properties of suspended graphene sheets. We find that already for deflections of the order of 0.5∈Å a theory that correctly accounts for nonlinearities is necessary and that for many purposes a set of coupled Duffing-type equations may be used to accurately describe the dynamics of graphene membranes. The descriptions are validated by applying them to square graphene-based resonators with clamped edges and studying numerically their mechanical responses. Both static and dynamic responses are treated, and we find good agreement with recent experimental findings. © 2010 Springer Science+Business Media B.V.
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| 4. |
- Atalaya, Juan, 1981, et al.
(författare)
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Nanomechanical mass measurement using nonlinear response of a graphene membrane
- 2010
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Ingår i: Europhysics Letters. - : IOP Publishing. - 0295-5075 .- 1286-4854. ; 91:4
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Tidskriftsartikel (refereegranskat)abstract
- We propose a scheme to measure the mass of a single particle using the nonlinear response of a 2D nanoresonator with degenerate eigenmodes. Using numerical and analytical calculations, we show that by driving a square graphene nanoresonator into the nonlinear regime, simultaneous determination of the mass and position of an added particle is possible. Moreover, this scheme only requires measurements in a narrow frequency band near the fundamental resonance.
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| 5. |
- Axelsson, S., et al.
(författare)
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Theoretical and experimental investigations of three-terminal carbon nanotube nanorelays
- 2005
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Ingår i: New J. Phys. - : IOP Publishing. - 1367-2630. ; 7
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Tidskriftsartikel (refereegranskat)abstract
- We present theoretical and experimental investigations of three-terminal nanoelectromechanical relays based on suspended carbon nanotubes. A charge is induced in the nanotube by applying a voltage to an underlying gate electrode thus inducing the nanotube to bend and make contact with a drain electrode. Such devices have potential applications as fast switches, logic devices, memory elements and pulse generators. We describe two modes of operation: a contact mode where the nanotube makes physical contact with the drain electrode and a non-contact mode where electrical contact between the nanotube and the drain electrode is made via a field emission current.
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| 6. |
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| 7. |
- Croy, Alexander, 1981, et al.
(författare)
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Nonlinear damping in graphene resonators
- 2012
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Ingår i: Physical Review B - Condensed Matter and Materials Physics. - 2469-9950 .- 2469-9969. ; 86:23, s. Article Number: 235435-
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Tidskriftsartikel (refereegranskat)abstract
- Based on a continuum mechanical model for single-layer graphene, we propose and analyze a microscopic mechanism for dissipation in nanoelectromechanical graphene resonators. We find that coupling between flexural modes and in-plane phonons leads to linear and nonlinear damping of out-of-plane vibrations. By tuning external parameters such as bias and ac voltages, one can cross over from a linear-to a nonlinear-damping dominated regime. We discuss the behavior of the effective quality factor in this context. DOI: 10.1103/PhysRevB.86.235435
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| 8. |
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| 9. |
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| 10. |
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| 11. |
- Eriksson, Anders, 1975, et al.
(författare)
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Direct Transmission Detection of Tunable Mechanical Resonance in an Individual Carbon Nanofiber Relay
- 2008
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Ingår i: Nano Letters. - : American Chemical Society (ACS). - 1530-6984 .- 1530-6992. ; 8
-
Tidskriftsartikel (refereegranskat)abstract
- A direct on-chip transmission measurement of the resonance frequency of an individual singly clamped carbon nanofiber relay is reported. The experimental results are in good agreement with a small signal model and show the expected tuning of the resonance frequency with changing bias voltage.
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| 12. |
- Ferrari, A. C., et al.
(författare)
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Science and technology roadmap for graphene, related two-dimensional crystals, and hybrid systems
- 2015
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Ingår i: Nanoscale. - : Royal Society of Chemistry (RSC). - 2040-3372 .- 2040-3364. ; 7:11, s. 4598-4810
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Tidskriftsartikel (refereegranskat)abstract
- We present the science and technology roadmap for graphene, related two-dimensional crystals, and hybrid systems, targeting an evolution in technology, that might lead to impacts and benefits reaching into most areas of society. This roadmap was developed within the framework of the European Graphene Flagship and outlines the main targets and research areas as best understood at the start of this ambitious project. We provide an overview of the key aspects of graphene and related materials (GRMs), ranging from fundamental research challenges to a variety of applications in a large number of sectors, highlighting the steps necessary to take GRMs from a state of raw potential to a point where they might revolutionize multiple industries. We also define an extensive list of acronyms in an effort to standardize the nomenclature in this emerging field.
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| 13. |
- Huldt, Caroline, 1976, et al.
(författare)
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Electronic transport in a shuttle with a discrete energy spectrum
- 2009
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Ingår i: New Journal of Physics. - : IOP Publishing. - 1367-2630. ; 11, s. 013060-
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Tidskriftsartikel (refereegranskat)abstract
- We present a multiscale approach for a molecular nanoelectromechanical shuttle, which takes into account the discrete energy levels and realistic orbitals of a specific molecular system. We deploy a Cu13 cluster as a central island and describe the electrodes within the jellium model. The shuttling features are then examined for a wide spectrum of bias voltages. The microscopic data of the cluster are obtained with density functional theory (DFT) while the macroscopic part combines stochastic charge dynamics, based on the microscopically evaluated tunnelling rates, with Newtonian dynamics. We find four transport regimes within the analysed bias voltage interval: a blocked regime (Vbias≤ 2 V), a pure shuttling regime (3 V ≤Vbias≤ 4 V), a mixed regime (5 V ≤Vbias≤ 6 V) and a direct tunnelling regime (Vbias≥7 V). In the two latter cases, the shuttling motion leads to a reduced current as compared to an island with a fixed position. The transport characteristics are strongly coupled to the availability of energetically allowed channels and the system therefore depends strongly on the microscopic details and bias voltages. For the setup at hand, however, the shuttling transport of one electron is ubiquitous and stable for all but the blocked regime.
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| 14. |
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| 15. |
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| 16. |
- Isacsson, Andreas, 1975, et al.
(författare)
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Electronic superlattices in corrugated graphene
- 2008
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Ingår i: Physical Review B. - 1098-0121. ; 77:3, s. 035423-
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Tidskriftsartikel (refereegranskat)abstract
- We theoretically investigate electron transport through corrugated graphene ribbons and show how the ribbon curvature leads to an electronic superlattice with a period set by the corrugation wavelength. Transport through the ribbon depends sensitively on the superlattice band structure which, in turn, strongly depends on the geometry of the deformed sheet. In particular, we find that for ribbon widths where the transverse level separation is comparable to the band edge energy, a strong current switching occurs as a function of an applied back gate voltage. Thus, artificially corrugated graphene sheets or ribbons can be used for the study of Dirac fermions in periodic potentials. Furthermore, this provides an additional design degree of freedom for graphene-based electronics.
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| 17. |
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| 18. |
- Isacsson, Andreas, 1975, et al.
(författare)
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Parametric resonances in electrostatically interacting carbon nanotube arrays
- 2009
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Ingår i: Physical Review B - Condensed Matter and Materials Physics. - 2469-9950 .- 2469-9969. ; 79:16, s. 165418-
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Tidskriftsartikel (refereegranskat)abstract
- We study, numerically and analytically, a model of a one-dimensional array of carbon nanotube resonators in a two-terminal configuration. The system is brought into resonance upon application of an ac signal superimposed on a dc bias voltage. When the tubes in the array are close to each other, electrostatic interactions between tubes become important for the array dynamics. We show that both transverse and longitudinal parametric resonances can be excited in addition to primary resonances. The intertube electrostatic interactions couple modes in orthogonal directions and affect the mode stability.
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| 19. |
- Isacsson, Andreas, 1975, et al.
(författare)
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Scaling properties of polycrystalline graphene: A review
- 2017
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Ingår i: 2D Materials. - : IOP Publishing. - 2053-1583. ; 4:1
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Forskningsöversikt (refereegranskat)abstract
- We present an overview of the electrical, mechanical, and thermal properties of polycrystalline graphene. Most global properties of this material, such as the charge mobility, thermal conductivity, or Young's modulus, are sensitive to its microstructure, for instance the grain size and the presence of line or point defects. Both the local and global features of polycrystalline graphene have been investigated by a variety of simulations and experimental measurements. In this review, we summarize the properties of polycrystalline graphene, and by establishing a perspective on how the microstructure impacts its large-scale physical properties, we aim to provide guidance for further optimization and improvement of applications based on this material, such as flexible and wearable electronics, and high-frequency or spintronic devices.
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| 20. |
- Jonsson, Magnus, 1979, et al.
(författare)
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Effects of short range forces on a three-terminal nanorelay
- 2003
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Ingår i: Fullerenes vol. 13 -- Fullerenes and Nanotubes: The Building Blocks of Next Generation Nanodevices. - 1566773970 ; , s. 432-439
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- We have performed a theoretical analysis of the operational characteristics of a carbon-nanotube-based three-terminal nanorelay. In the present study we focus on introducing short range forces into the model. We show is that these forces have a significant impact on the characteristics of the relay. We also investigate the nanorelay as a memory element, and conclude that this is a promising application.
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| 21. |
- Jonsson, Magnus, 1979, et al.
(författare)
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Effects of surface forces and phonon dissipation in a three-terminal nanorelay
- 2004
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Ingår i: Journal of Apllied Physics. ; 96, s. 629-
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Tidskriftsartikel (refereegranskat)abstract
- We have performed a theoretical analysis of the operational characteristics of a carbonnanotube-based three-terminal nanorelay. We show that short range and van der Waals forces have a significant impact on the characteristics of the relay and introduce design constraints. We also investigate the effects of dissipation due to phonon excitation in the drain contact, which changes the switching time scales of the system, decreasing the longest time scale by 2 orders of magnitude. We show that the nanorelay can be used as a memory element and investigate the dynamics and properties of such a device.
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| 22. |
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| 23. |
- Kaunisto, R., et al.
(författare)
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Nanotube Device
- 2010
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Patent (övrigt vetenskapligt/konstnärligt)
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| 24. |
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| 25. |
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| 26. |
- Kinaret, Jari, 1962, et al.
(författare)
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Graphene-driven revolutions in ICT and beyond
- 2011
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Ingår i: Procedia Computer Science, 2nd European Future Technologies Conference and Exhibition 2011, FET 11, Budapest; 4 May through 6 May 2011. - : Elsevier BV. - 1877-0509. ; 7, s. 30-33
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Konferensbidrag (refereegranskat)abstract
- This session described the FET Flagship Pilot on graphene and related two-dimensional materials. The flagship targets a revolution in information and communication technology, with impacts reaching into other areas of the society. The session featured four talks on the scientific and technological potential and open research challenges within the scope of the proposed flagship, industrial view on possibilities and challenges posed by graphene and related materials, and presentation on the implementation and structure of the flagship pilot.
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| 27. |
- Kinaret, Jari, 1962, et al.
(författare)
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Il futuro? Una questione di chimica
- 2015
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Ingår i: Il Sole 24 ore. - 0391-786X. ; 2015:december 6, s. 11-
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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| 28. |
- Kinaret, Jari, 1962
(författare)
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Practise the art of incisive questions
- 2015
-
Ingår i: Nature. - 0028-0836 .- 1476-4687. ; 523, s. 371-373
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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| 29. |
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| 30. |
- Lassagne, Benjamin, et al.
(författare)
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Coupling Mechanics to Charge Transport in Carbon Nanotube Mechanical Resonators
- 2009
-
Ingår i: Science. - 0036-8075 .- 1095-9203. ; 325, s. 1107-1110
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Tidskriftsartikel (refereegranskat)abstract
- Nanoelectromechanical resonators have potential applications in sensing, cooling, and mechanicalsignal processing. An important parameter in these systems is the strength of coupling the resonatormotion to charge transport through the device. We investigated the mechanical oscillations of asuspended single-walled carbon nanotube that also acts as a single-electron transistor. The couplingof the mechanical and the charge degrees of freedom is strikingly strong as well as widely tunable(the associated damping rate is ~3 MHz). In particular, the coupling is strong enough to drivethe oscillations in the nonlinear regime.
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| 31. |
- Midtvedt, Daniel, 1988, et al.
(författare)
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Parametric Resonance in Nanoelectromechanical Single Electron Transistors
- 2011
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Ingår i: Nano Letters. - : American Chemical Society (ACS). - 1530-6992 .- 1530-6984. ; 11:4, s. 1439-1442
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Tidskriftsartikel (refereegranskat)abstract
- We show that the coupling between single-electron charging and mechanical motion in a nanoelectromechanical single-electron transistor can be utilized in a novel parametric actuation scheme. This scheme, which relies on a periodic modulation of the mechanical resonance frequency through an alternating source drain voltage, leads to a parametric instability and emergence of mechanical vibrations in a limited range of modulation amplitudes. Remarkably, the frequency range where instability occurs and the maximum oscillation amplitude, depend weakly on the damping in the system. We also show that a weak parametric modulation increases the effective quality factor and amplifies the system's response to the conventional actuation that exploits an AC gate signal.
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| 32. |
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| 33. |
- Rehammar, Robert, 1980, et al.
(författare)
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Carbon nanofiber-based photonic crystals – fabrication, diffraction and ellipsometry investigations
- 2011
-
Ingår i: Carbon-Based Electronic Devices - Processing, Performance and Reliability. - : Materials Research Society. - 0272-9172. - 9781618394996 ; , s. 28-33
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Konferensbidrag (refereegranskat)abstract
- Carbon nanofibers were used as building blocks for two-dimensional photonic crystal slabs. Electron beam lithography and chemical vapor deposition were used to fabricate regular arrays and random patterns of nanofibers. The optical properties of the samples were investigated using a diffraction measurement setup, as well as reflection ellipsometry. We find that carbon nanofiber regularity has a strong effect on both diffractive and specular optical properties. This shows that ellipsometry can be a valuable tool to study properties of carbon nanofiber arrays. It also shows that carbon nanofibers provide an interesting candidate as building blocks for nanostructured optical components.
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| 34. |
- Rehammar, Robert, 1980, et al.
(författare)
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Diffraction from carbon nanofiber arrays
- 2012
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Ingår i: Optics Letters. - 0146-9592 .- 1539-4794. ; 37:1, s. 100-102
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Tidskriftsartikel (refereegranskat)abstract
- We fabricate a square planar photonic crystal (PC) from carbon nanofibres (CNFs) using e-beam lithography and chemical vapour deposition and investigate the optical properties of this system. The system exhibit diffraction that is well described by diffraction theory. We measure the intensity of the (-1,0) and (-1,-1) diffraction spots as functions of angle of incidence. The radiation diagram obtained can be explained by interference between different diffraction beams. We observe a polarisation dependence of the intensity. In conclusion we suggest future applications of these structures.
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| 35. |
- Rehammar, Robert, 1980, et al.
(författare)
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Electromechanically Tunable Carbon Nanofiber Photonic Crystal
- 2013
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Ingår i: Nano letters (Print). - : AMER CHEMICAL SOC. - 1530-6984 .- 1530-6992. ; 13:2, s. 397-401
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Tidskriftsartikel (refereegranskat)abstract
- We demonstrate an electrically tunable 2D photonic crystal array constructed from vertically alignedcarbon nanofibers. The nanofibers are actuated by applying a voltage between adjacent carbon nanofiberpairs grown directly on metal electrodes, thus dynamically changing the form factor of the photoniccrystal lattice. The change in optical properties is characterised using optical diffraction andellipsometry. The experimental results are shown to be in agreement with theoretical predictions andprovide a proof-of-principle for rapidly switchable photonic crystals operating in the visible that can befabricated using standard nanolithography techniques combined with plasma CVD growth of thenanofibers.
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| 36. |
- Rehammar, Robert, 1980, et al.
(författare)
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Nanowire-based tunable photonic crystals
- 2008
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Ingår i: Optics Express. ; 16:26, s. 21682-21691
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Tidskriftsartikel (refereegranskat)abstract
- Photonic crystals, materials with periodically varying refractive indices, show exciting optical properties that enable many technological applications. Conventional photonic crystals have optical properties that are determined at the time of fabrication and the ability to tune them is quite limited, particularly at visible frequencies. We investigate theoretically the possibility to use nanowires or nanotubes as the building block for tunable two-dimensional photonic crystals. Tunability is achieved by fabricating flexible nanowires in a periodic pattern and actuating them electrostatically. This changes the lattice basis, which in turn modifies the optical properties of the photonic crystal. We use a finite-difference time-domain method to model photonic crystals with changeable bases. We show that the optical transmission through a two-dimensional photonic crystal with only a few rows of nanowires in the light propagating direction can be electrostatically tuned from over 90% transmission to less than 10%. We demonstrate that tunability is maintained in realistic three-dimensional experimental geometries. Finally, we analyse the performance of the photonic crystals in terms of actuation voltages and tuning speeds, and conclude that the response time of a tunable carbon-nanofibre-based photonic crystal lies in the microsecond range.
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| 37. |
- Rehammar, Robert, 1980, et al.
(författare)
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Optical properties of carbon nanofiber photonic crystals
- 2010
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Ingår i: NANOTECHNOLOGY. - : Institute of Physics; 1999. - 0957-4484 .- 1361-6528. ; 21:46, s. 465203-
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Tidskriftsartikel (refereegranskat)abstract
- Carbon nanofibers (CNFs) are used as components of planar photonic crystals. Square and rectangular lattices and random patterns of vertically aligned CNFs were fabricated and their properties studied using ellipsometry. We show that detailed information such as symmetry directions and the band structure of these novel materials can be extracted from considerations of the polarization state in the specular beam. The refractive index of the individual nanofibers was found to be n(CNF) = 4.1.
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| 38. |
- Samadikhah, Kaveh, 1982, et al.
(författare)
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General elasticity theory for graphene membranes based on molecular dynamics
- 2007
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Ingår i: Materials Research Society Symposium Proceedings. - 0272-9172. - 9781605608266 ; , s. 109-114
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Konferensbidrag (refereegranskat)abstract
- We have studied the mechanical properties of suspended graphene membranes using molecular dynamics (MD) and generalized continuum elasticity theory (GE) in order to develop and assess a continuum description for graphene. The MD simulations are based on a valence force field model which is used to determine the deformation and the elastic energy of the membrane (EMD) as a function of external forces. For the continuum description, we use the expression Econt = Estretching + Ebending for the elastic energy functional. The elastic parameters (tensile rigidity and Poisson ratio) entering Econt are determined by requiring that E cont = EMD for a set of deformations. Comparisons with the MD results show excellent agreement. We find that the elastic energy of a supported graphene sheets is typically dominated by the nonlinear stretching terms whereas a linear description is valid only for very small deflections. This implies that in some applications, i.e. NEMS, a linear description is of limited applicability.
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| 39. |
- Svensson, Johannes, 1978, et al.
(författare)
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A carbon nanotube gated carbon nanotube transistor with 5 ps gate
- 2008
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Ingår i: Nanotechnology. - : IOP Publishing. - 0957-4484 .- 1361-6528. ; 19
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Tidskriftsartikel (refereegranskat)abstract
- Semiconducting carbon nanotubes (CNTs) are attractive as channel material for field-effect transistors due to their high carrier mobility. In this paper we show that a local CNT gate can provide a significant improvement in the subthreshold slope of a CNT transistor compared to back gate switching and provide gate delays as low as 5 ps. The CNT gated CNT transistor devices are fabricated using a two-step chemical vapour deposition technique. The measured transfer characteristics are in very good agreement with theoretical modelling results that provide confirmation of the operating principle of the transistors. Gate delays below 2 ps should be readily achievable by reducing the thickness of the gate dielectric.
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| 40. |
- Svensson, Johannes, et al.
(författare)
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Carbon Nanotube Field Effect Transistors with Suspended Graphene Gates
- 2011
-
Ingår i: Nano Letters. - : American Chemical Society (ACS). - 1530-6992 .- 1530-6984. ; 11:9, s. 3569-3575
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Tidskriftsartikel (refereegranskat)abstract
- Novel field effect transistors with suspended graphene gates are demonstrated. By incorporating mechanical motion of the gate electrode, it is possible to improve the switching characteristics compared to a static gate, as shown by a combination of experimental measurements and numerical simulations. The mechanical motion of the graphene gate is confirmed by using atomic force microscopy to directly measure the electrostatic deflection. The device geometry investigated here can also provide a sensitive measurement technique for detecting high-frequency motion of suspended membranes as required, e.g., for mass sensing.
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| 41. |
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| 42. |
- Viefers, Susanne, 1970, et al.
(författare)
-
ELECTROMECHANICAL NANOTUBE TUNNELING DEVICE COMPRISING SOURCE, DRAIN AND GATE
- 2011
-
Patent (övrigt vetenskapligt/konstnärligt)abstract
- The present invention relates to a nanotube device (100) comprising a nanotube with a longitudinal and a lateral extension, a structure for supporting at least a first part of the nanotube, and first means for exerting a force upon the nanotube in a first direction defined by its lateral extension. At least a second part of the nanotube protrudes beyond the support of said structure, so that when said force exceeds a certain level, the second part of the nanotube will flex in the direction of its lateral extension, and thereby close a first electrical circuit. Suitably, the first means for exerting said force upon the nanotube is an electrical means, the force being created by applying a voltage to the means. The device allows for quantum mechanics tunnel effects, both at a source and at a drain electrode.
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| 43. |
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| 44. |
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| 45. |
- Viefers, Susanne, 1970, et al.
(författare)
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Nanotube relay device
- 2007
-
Patent (övrigt vetenskapligt/konstnärligt)
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| 46. |
- Viola, Giovanni, 1982, et al.
(författare)
-
Graphene plasmons: Impurities and nonlocal effects
- 2018
-
Ingår i: Physical Review B - Condensed Matter and Materials Physics. - 2469-9950 .- 2469-9969. ; 97:8
-
Tidskriftsartikel (refereegranskat)abstract
- This work analyzes how impurities and vacancies on the surface of a graphene sample affect its optical conductivity and plasmon excitations. The disorder is analyzed in the self-consistent Green’s function formulation and nonlocal effects are fully taken into account. It is shown that impurities modify the linear spectrum and give rise to an impurity band whose position and width depend on the two parameters of our model, the density and the strength of impurities. The presence of the impurity band strongly influences the electromagnetic response and the plasmon losses. Furthermore, we discuss how the impurity-band position can be obtained experimentally from the plasmon dispersion relation and discuss this in the context of sensing.
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| 47. |
- Viola, Giovanni, 1982, et al.
(författare)
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Graphene plasmons in the presence of adatoms
- 2017
-
Ingår i: New Journal of Physics. - : IOP Publishing. - 1367-2630. ; 19:7, s. Article no 073027 -
-
Tidskriftsartikel (refereegranskat)abstract
- We theoretically investigate graphene plasmons in the presence of a low density of adatoms on the graphene surface. The adatoms can significantly modify the conductivity and plasmonic properties of graphene and may produce a level splitting with the plasmon mode, resulting in two plasmon branches. The high energy branch exhibits large losses and the low energy branch exhibits low losses. Our model may also be considered as a simple model for molecules on graphene and we show that graphene plasmons are sensitive to such changes in the environment. Our microscopic treatment of plasmons and adatoms shows the sensitivity of plasmons and highlights the potential of graphene plasmons for sensing purposes.
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| 48. |
- Voje, Aurora, 1985, et al.
(författare)
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Generating macroscopic superposition states in nanomechanical graphene resonators
- 2012
-
Ingår i: Physical Review B - Condensed Matter and Materials Physics. - 2469-9950 .- 2469-9969. ; 85:20
-
Tidskriftsartikel (refereegranskat)abstract
- A theoretical study of the quantum dynamics of a symmetric nanomechanical graphene resonator with degenerate flexural modes is presented. Applying voltage pulses to two back gates, flexural vibrations of the membrane can be selectively actuated and manipulated. For graphene, nonlinear response becomes important for amplitudes comparable to the magnitude of zero-point fluctuations. We show, using analytical and numerical methods, that this allows for creation of catlike superpositions of coherent states as well as superpositions of coherent catlike nonproduct states.
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| 49. |
- Wang, Weihua, 1981, et al.
(författare)
-
Edge magnetoplasmons and the optical excitations in graphene disks
- 2012
-
Ingår i: Physical Review B - Condensed Matter and Materials Physics. - 2469-9950 .- 2469-9969. ; 86:12
-
Tidskriftsartikel (refereegranskat)abstract
- We discuss the edge magnetoplasmon properties in highly doped graphene disks, and the corresponding optical excitations. Edge magnetoplasmons with nonzero angular momentum (l not equal 0) have two branches corresponding to different edge current rotations with respect to the magnetic field. The resonance energies of one branch are blueshifted and the other redshifted relative to energies at B = 0, with the energy differences linearly proportional to the magnetic field. Recently, the l = 1 dipole mode has been investigated by two experiments using optical transmission spectroscopy [Crassee et al., Nano Lett. 12, 2470 (2012); Yan et al., ibid. 12, 3766 (2012)], and classical cyclotron resonances were found in highly doped graphene samples. These are determined by graphene magneto-optical conductivities, which behave like a conventional two-dimensional electron system in the high doping limit.
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| 50. |
- Wang, Weihua, 1981, et al.
(författare)
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Excitation of edge magnetoplasmons in semi-infinite graphene sheets: Temperature effects
- 2012
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Ingår i: Physical Review B - Condensed Matter and Materials Physics. - 2469-9950 .- 2469-9969. ; 85:23, s. art. no. 235444-
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Tidskriftsartikel (refereegranskat)abstract
- We investigate edge magnetoplasmons in semi-infinite graphene sheets. Similar to an ordinary two-dimensional electron system (2DES), at zero temperature graphene sheets exhibit two magnetoplasmon branches, a higher-energy one starting at the n = 1 Landau level (cyclotron frequency) and a lower-energy edge branch starting at zero frequency. However, in contrast to a 2DES with parabolic dispersion, at nonzero temperatures an extra magnetoplasmon branch arises at the n = 1 Landau level and has the same edge current rotation as the lower-energy branch.
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