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| 2. |
- Drexler, C., et al.
(författare)
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Magnetic quantum ratchet effect in graphene
- 2013
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Ingår i: Nature Nanotechnology. - 1748-3387 .- 1748-3395. ; 8:2, s. 104-107
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Tidskriftsartikel (refereegranskat)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.
(författare)
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Magnetic quantum ratchet effect in graphene
- 2013
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Ingår i: International Conference on Infrared, Millimeter, and Terahertz Waves, IRMMW-THz. - 2162-2027 .- 2162-2035. - 9781467347174
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Konferensbidrag (refereegranskat)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. |
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| 5. |
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| 6. |
- Drexler, C, et al.
(författare)
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Magnetic quantum ratchet effect in graphene
- 2013
-
Ingår i: Nature Nanotechnology. - : Nature Publishing Group. - 1748-3387 .- 1748-3395. ; 8:2, s. 104-107
-
Tidskriftsartikel (refereegranskat)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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| 7. |
- Gingl, Z, et al.
(författare)
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A self-adaptive stochastic resonator with logarithmic transfer
- 2000
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Ingår i: CHAOS SOLITONS & FRACTALS. - : PERGAMON-ELSEVIER SCIENCE LTD. - 0960-0779. ; 11:12, s. 1933-1935
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Tidskriftsartikel (refereegranskat)abstract
- We introduce a new self-adaptive stochastic resonator system as a simple model for sensing mechanisms. The model is based on a level-crossing detector (LCD) with stepwise, dynamically increasing and relaxing threshold level after each firing event. The tr
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| 8. |
- Gingl, Z, et al.
(författare)
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Signal-to-noise ratio gain by stochastic resonance in a bistable system
- 2000
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Ingår i: CHAOS SOLITONS & FRACTALS. - : PERGAMON-ELSEVIER SCIENCE LTD. - 0960-0779. ; 11:12, s. 1929-1932
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Tidskriftsartikel (refereegranskat)abstract
- It was shown recently that the signal-to-noise ratio (SNR) could be improved by stochastic resonance (SR) in certain monostable systems and certain systems with monotonous nonlinearity working in the nonlinear response (NLR) regime. Here we demonstrate th
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| 11. |
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| 13. |
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| 14. |
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| 15. |
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| 16. |
- Kish, L.B., Otten, F., Vandamme, L.K.J., Vajtai, R., Granqvist, C.G., Marlow, B., Kruis, E., Fissan, H., Ederth, J., Chaoguang, P.
(författare)
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Noise Measurements and Fluctuation Analysis in Nanoparticle Films
- 2001
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Ingår i: Advanced Research Workshop on Semiconductor Nanostructures, 2001, New Zealand. Paper presented by L.B. Kish, as an invited talk, at the Advanced Research Workshop on Semiconductor Nanostructures, 5-9 February, 2001, Qeenstown, New Zealand..
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)
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| 17. |
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| 18. |
- Kish, L.B., Solis, J.L., Vajtai, R., Granqvist, C.G., Olsson, J., Schnurer, J., Lantto, V., Marlow, W.H., Gingl, Z.
(författare)
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How can noise “smell” and remember that “smell”
- 2001
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Ingår i: 16th International Conference on Noise in Physical Systems and 1/f Fluctuations, Gainesville Florida, October 22-25, 2001. Paper to be presented by L.B. Kish..
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)
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| 19. |
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| 20. |
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| 21. |
- Kish, LB, et al.
(författare)
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Noise measurements and fluctuation analysis in nanoparticle films
- 2001
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Ingår i: PHYSICA E. - : ELSEVIER SCIENCE BV. - 1386-9477. ; 11:2-3, s. 131-136
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Tidskriftsartikel (refereegranskat)abstract
- This work reports two different ways of study providing potentially important information about nanoparticle films. The first study is about conductance noise in PbS nanoparticle films. Monocrystalline and single-sized PbS nanoparticles are synthesized vi
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| 22. |
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| 23. |
- Kordas, K., et al.
(författare)
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Magnetic-field induced efficient alignment of carbon nanotubes in aqueous solutions
- 2007
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Ingår i: Chemistry of Materials. - : American Chemical Society (ACS). - 0897-4756 .- 1520-5002. ; 19:4, s. 787-791
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Tidskriftsartikel (refereegranskat)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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| 24. |
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| 25. |
- Roumiantsev, S., Vajtai, R., Pala, N., Wei, B.Q., Shur, M.S., Kish, L.B., Ajayan, P.M.
(författare)
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Noise properties of ironfilled carbon nanotubes
- 2001
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Ingår i: International Symposium “Nanostructures: Physics and Technology”, St. Petersburg, Russia, 18-22 June 2001. Paper to be presented by S. Roumiantsev..
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)
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| 26. |
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| 27. |
- Solis, J. L., et al.
(författare)
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Identifying natural and artificial odours through noise analysis with a sampling-and-hold electronic nose
- 2001
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Ingår i: Sensors and actuators. B, Chemical. - : Elsevier. - 0925-4005 .- 1873-3077. ; 77:1-2, s. 312-315
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Tidskriftsartikel (refereegranskat)abstract
- A sampling-and-hold type electronic nose was used to investigate "frozen" sensor dynamics. The sensor was heated to the sensing temperature and exposed to a chemical environment for a short time. Then, while keeping the sensor in the chemical environment, the heating was switched off so that the sensor cooled down to room temperature. Chemicals species become trapped in the sensor film, and therefore, the current transport in the film is changed. The trapped chemicals are usually located at grain boundaries, and they influence the charge transport in the grains and between the grains. This gives random fluctuations to the local conductivity. Resistance noise was employed to extract chemical information from the sensor in the cold state.
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