| 1. |
- Drexler, C, et al.
(author)
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Magnetic quantum ratchet effect in graphene
- 2013
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In: Nature Nanotechnology. - : Nature Publishing Group. - 1748-3387 .- 1748-3395. ; 8:2, s. 104-107
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Journal article (peer-reviewed)abstract
- A periodically driven system with spatial asymmetry can exhibit a directed motion facilitated by thermal or quantum fluctuations(1). This so-called ratchet effect(2) has fascinating ramifications in engineering and natural sciences(3-18). Graphene(19) is nominally a symmetric system. Driven by a periodic electric field, no directed electric current should flow. However, if the graphene has lost its spatial symmetry due to its substrate or adatoms, an electronic ratchet motion can arise. We report an experimental demonstration of such an electronic ratchet in graphene layers, proving the underlying spatial asymmetry. The orbital asymmetry of the Dirac fermions is induced by an in-plane magnetic field, whereas the periodic driving comes from terahertz radiation. The resulting magnetic quantum ratchet transforms the a.c. power into a d.c. current, extracting work from the out-of-equilibrium electrons driven by undirected periodic forces. The observation of ratchet transport in this purest possible two-dimensional system indicates that the orbital effects may appear and be substantial in other two-dimensional crystals such as boron nitride, molybdenum dichalcogenides and related heterostructures. The measurable orbital effects in the presence of an in-plane magnetic field provide strong evidence for the existence of structure inversion asymmetry in graphene.
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| 2. |
- Drexler, C., et al.
(author)
-
Magnetic quantum ratchet effect in graphene
- 2013
-
In: Nature Nanotechnology. - 1748-3387 .- 1748-3395. ; 8:2, s. 104-107
-
Journal article (peer-reviewed)abstract
- A periodically driven system with spatial asymmetry can exhibit a directed motion facilitated by thermal or quantum fluctuations(1). This so-called ratchet effect(2) has fascinating ramifications in engineering and natural sciences(3-18). Graphene(19) is nominally a symmetric system. Driven by a periodic electric field, no directed electric current should flow. However, if the graphene has lost its spatial symmetry due to its substrate or adatoms, an electronic ratchet motion can arise. We report an experimental demonstration of such an electronic ratchet in graphene layers, proving the underlying spatial asymmetry. The orbital asymmetry of the Dirac fermions is induced by an in-plane magnetic field, whereas the periodic driving comes from terahertz radiation. The resulting magnetic quantum ratchet transforms the a.c. power into a d.c. current, extracting work from the out-of-equilibrium electrons driven by undirected periodic forces. The observation of ratchet transport in this purest possible two-dimensional system indicates that the orbital effects may appear and be substantial in other two-dimensional crystals such as boron nitride, molybdenum dichalcogenides and related heterostructures. The measurable orbital effects in the presence of an in-plane magnetic field provide strong evidence for the existence of structure inversion asymmetry in graphene.
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| 3. |
- Ganichev, S.D., et al.
(author)
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Magnetic quantum ratchet effect in graphene
- 2013
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In: International Conference on Infrared, Millimeter, and Terahertz Waves, IRMMW-THz. - 2162-2027 .- 2162-2035. - 9781467347174
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Conference paper (peer-reviewed)abstract
- We report on the observation of magnetic quantum ratchet (MQR) effect induced by electric field of terahertz radiation in single-layer graphene samples subjected to an inplane magnetic field. We show that the dc electric current stems from the orbital asymmetry of the Dirac fermions induced by an in-plane magnetic field, while the periodic driving comes from terahertz radiation. A microscopic theory of the observed effect is developed being in a good qualitative agreement with the experiment. The observation of the ratchet transport in the purest possible two-dimensional system indicates that the orbital effects may appear and be substantial in other 2D crystals, such as boron nitride, molybdenum dichalcogenides, and related heterostructures. The measurable orbital effects in the presence of an in-plane magnetic field give strong evidence for the existence of structure inversion asymmetry in graphene.
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| 4. |
- Chakravarty, D., et al.
(author)
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Zirconia-Nanoparticle-Reinforced Morphology-Engineered Graphene-Based Foams
- 2015
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In: Advanced Materials. - : Wiley. - 0935-9648. ; 27:31, s. 4534-4543
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Journal article (peer-reviewed)abstract
- The morphology of graphene-based foams can be engineered by reinforcing them with nanocrystalline zirconia, thus improving their oil-adsorption capacity; This can be observed experimentally and explained theoretically. Low zirconia fractions yield flaky microstructures where zirconia nanoparticles arrest propagating cracks. Higher zirconia concentrations possess a mesh-like interconnected structure where the degree of coiling is dependant on the local zirconia content. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
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| 5. |
- Roumiantsev, S., Vajtai, R., Pala, N., Wei, B.Q., Shur, M.S., Kish, L.B., Ajayan, P.M.
(author)
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Noise properties of ironfilled carbon nanotubes
- 2001
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In: International Symposium “Nanostructures: Physics and Technology”, St. Petersburg, Russia, 18-22 June 2001. Paper to be presented by S. Roumiantsev..
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Conference paper (other academic/artistic)
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| 6. |
- Khossossi, Nabil, et al.
(author)
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Exploring the Possibility of beta-Phase Arsenic-Phosphorus Polymorph Monolayer as Anode Materials for Sodium-Ion Batteries
- 2020
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In: Advanced Theory and Simulations. - : Wiley-VCH Verlag. - 2513-0390. ; 3:8
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Journal article (peer-reviewed)abstract
- Graphite anode have shown commercial success for over two decades, since the start of their use in commercial Li-ion batteries, due to their high practical specific capacity, conductivity, and low lithiation potential. Graphite is to a large extent thermodynamically unfavorable for sodium-ion intercalation and thus limits advancement in Na-ion batteries. In this work, a beta-phase arsenic-phosphorus monolayer is studied, which has recently been predicted to have semiconducting behavior and to be dynamically stable. First-principles calculations based on density functional theory are used to explore the role of beta-AsP monolayer as a negative electrode for Na-ion batteries. Cohesive energy, phonon spectrum, and molecule dynamics simulations confirm the thermodynamic stability and the possibility of experimentally synthesizing this material. The Na-ion adsorption-energies are found to be high (>-1.2 eV) on both sides (As- and P-side). The ultra-fast energy barriers for Na (0.046/0.053 V) over both sides imply high diffusion of Na-ions on the surfaces of beta-AsP. During the evaluation of Na-ion anode performance, the fully sodiated state is found to be Na2AsP, which yields a high theoretical-specific capacity of 506.16 mAh g(-1)and low average sodiation potential of 0.43 V versus Na/Na+.
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| 7. |
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| 8. |
- Kordas, K., et al.
(author)
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Magnetic-field induced efficient alignment of carbon nanotubes in aqueous solutions
- 2007
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In: Chemistry of Materials. - : American Chemical Society (ACS). - 0897-4756 .- 1520-5002. ; 19:4, s. 787-791
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Journal article (peer-reviewed)abstract
- Efficient alignment of aqueous carboxyl-functionalized multiwalled carbon nanotubes having remanent iron catalyst particles are carried out in relatively low external magnetic fields (B <= 1017 mT). The nanotubes were grown by catalytic chemical vapor deposition and then functionalized in a multistep oxidation process using nitric acid and potassium permanganate. In the field-induced ordering, the ferromagnetic property of iron nanoparticles entrapped in the inner-tubular cavity of nanotubes is exploited. Considerable dichroism of nanotube solutions (up to 3.02) is measured and deposition of aligned CNT networks from the solutions on silicon substrates is demonstrated.
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