| 1. |
- Kadigrobov, Anatoli M., 1937, et al.
(författare)
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Hot electrons in magnetic point contacts as a photon source
- 2011
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Ingår i: New Journal of Physics. - : IOP Publishing. - 1367-2630. ; 13
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Tidskriftsartikel (refereegranskat)abstract
- We propose to use a point contact between a ferromagnetic and a normal metal in the presence of a magnetic field for creating a large inverted spin population of hot electrons in the contact core. The key point of the proposal is that when these hot electrons relax by flipping their spin, microwave photons are emitted, with a frequency tunable by the applied magnetic field. While point contacts are an established technology, their use as a photon source is a new and potentially very useful application. We show that this photon emission process can be detected by means of transport spectroscopy and demonstrate stimulated emission of radiation in the 10–100 GHz range for a model point contact system using a minority-spin ferromagnetic injector. These results can potentially lead to new types of lasers based on spin injection in metals.
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| 2. |
- Shekhter, Robert I., 1947, et al.
(författare)
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Electronic spin working mechanically
- 2014
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Ingår i: Fizika Nizkikh Temperatur. - 0132-6414 .- 1816-0328. ; 40:7, s. 775-792
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Tidskriftsartikel (refereegranskat)abstract
- A single-electron tunneling (SET) device with a nanoscale central island that can move with respect to the bulk source- and drain electrodes allows for a nanoelectromechanical (NEM) coupling between the electrical current through the device and mechanical vibrations of the island. Although an electromechanical "shuttle" in-stability and the associated phenomenon of single-electron shuttling were predicted more than 15 years ago, both theoretical and experimental studies of NEM-SET structures are still carried out. New functionalities based on quantum coherence, Coulomb correlations and coherent electron-spin dynamics are of particular current interest. In this article we present a short review of recent activities in this area.
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| 3. |
- Shekhter, Robert I., 1947, et al.
(författare)
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Subwavelength terahertz spin-flip laser based on a magnetic point-contact array
- 2011
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Ingår i: Optics Letters. - 0146-9592 .- 1539-4794. ; 36:12, s. 2381-2383
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Tidskriftsartikel (refereegranskat)abstract
- We present a theoretical design for a single-mode, truly subwavelength terahertz disk laser based on a nanocomposite gain medium comprising an array of normal-metal/ferromagnetic (FM) point contacts embedded in a thin dielectric layer. Stimulated emission of light occurs due to spin-flip relaxation of spin-polarized electrons injected from the FM side of the contacts. Ultrahigh electrical current densities in the contacts and a dielectric material with a large refractive index, neither condition being achievable in conventional semiconductor media, enables the thresholds of lasing to be overcome for the lowest-order modes of the disk, making single-mode operation possible.
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| 4. |
- Dancet, Eline A F, et al.
(författare)
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The Role of Scientists and Clinicians in Raising Public Support for Animal Research in Reproductive Biology and Medicine.
- 2012
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Ingår i: Biology of reproduction. - : Oxford University Press (OUP). - 1529-7268 .- 0006-3363.
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Tidskriftsartikel (refereegranskat)abstract
- It is important that researchers active in reproductive animal research, as a group, clearly and compassionately convey specific information to students, patients, and the general public on the merit and need for biomedical research using various formats and seek active support from patient organizations, universities, politicians, celebrities, the media, and international professional organizations related to human and animal health.
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| 5. |
- Hudson, Lawrence N., et al.
(författare)
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The PREDICTS database : a global database of how local terrestrial biodiversity responds to human impacts
- 2014
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Ingår i: Ecology and Evolution. - : Wiley. - 2045-7758. ; 4:24, s. 4701-4735
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Tidskriftsartikel (refereegranskat)abstract
- Biodiversity continues to decline in the face of increasing anthropogenic pressures such as habitat destruction, exploitation, pollution and introduction of alien species. Existing global databases of species' threat status or population time series are dominated by charismatic species. The collation of datasets with broad taxonomic and biogeographic extents, and that support computation of a range of biodiversity indicators, is necessary to enable better understanding of historical declines and to project - and avert - future declines. We describe and assess a new database of more than 1.6 million samples from 78 countries representing over 28,000 species, collated from existing spatial comparisons of local-scale biodiversity exposed to different intensities and types of anthropogenic pressures, from terrestrial sites around the world. The database contains measurements taken in 208 (of 814) ecoregions, 13 (of 14) biomes, 25 (of 35) biodiversity hotspots and 16 (of 17) megadiverse countries. The database contains more than 1% of the total number of all species described, and more than 1% of the described species within many taxonomic groups - including flowering plants, gymnosperms, birds, mammals, reptiles, amphibians, beetles, lepidopterans and hymenopterans. The dataset, which is still being added to, is therefore already considerably larger and more representative than those used by previous quantitative models of biodiversity trends and responses. The database is being assembled as part of the PREDICTS project (Projecting Responses of Ecological Diversity In Changing Terrestrial Systems - ). We make site-level summary data available alongside this article. The full database will be publicly available in 2015.
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| 6. |
- Kadigrobov, Anatoli M., 1937, et al.
(författare)
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Giant lasing effect in magnetic point contacts and its detection by DC electrical measurements
- 2011
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Ingår i: Proc. of SPIE. - 0277-786X. - 9780819484703 ; 7933
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Konferensbidrag (refereegranskat)abstract
- We propose a new principle for a compact solid-state laser in 1-100 THz regime based on a new mechanism for creating spin-flip processes in ferromagnetic conductors. On the base of this mechanism, a giant lasing effect is predicted. The optical gain is estimated to exceed the optical gain of conventional semiconductor lasers by 4 or 5 orders of magnitude. We propose to use a point contact between ferromagnetic metals in order to create an inverted spin-population of hot electrons in the contact region. While point contact spectroscopy is an established technology the use of magnetic point contacts as a photon source is a new and potentially very useful application. We show that the generated photons conveniently can be detected by measuring the current through the illuminated point contact.
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| 7. |
- Kadigrobov, Anatoli M., 1937, et al.
(författare)
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Microwave-induced spin-flip scattering of electrons in point contacts
- 2011
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Ingår i: Low Temperature Physics. - 1063-777X. ; 37:11, s. 925-932
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Tidskriftsartikel (refereegranskat)abstract
- We investigate resonant interaction of conduction electrons with an electromagnetic field that irradiates a point contact between a ferromagnetic and a normal metal in the presence of a strong magnetic field of order 1 T. We show that electron spin-flips caused by resonant absorption and stimulated emission of photons result in a sharp peak in the magnetic-field dependence of the point-contact resistance. The height of the peak is shown to be directly proportional to the net rate of energy transfer to the electromagnetic field in the point contact due to absorption and stimulated emission of photons. Estimations indicate that our theory can serve as a basis for the explanation of recent experiments [A.M. Kadigrobov et al., New J. Phys. 13, 023007 (2011)].
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| 8. |
- Kulinich, Sergeij I., et al.
(författare)
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Nanomechanics of a magnetic shuttle device
- 2014
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Ingår i: Low temperature physics. - : AIP Publishing. - 1063-777X .- 1090-6517. ; 40:10, s. 1161-1169
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Tidskriftsartikel (refereegranskat)abstract
- We show that self sustained mechanical vibrations in a model magnetic shuttle device can be driven by both the charge and the spin accumulated on the movable central island of the device. Different scenarios for how spin- and charge-induced shuttle instabilities may develop are discussed and shown to depend on whether there is a Coulomb blockade of tunneling or not. The crucial role of electronic spin flips in a magnetically driven shuttle is established and shown to cause giant magnetoresistance and dynamic magnetostriction effects.
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| 9. |
- Kulinich, Sergeij I., et al.
(författare)
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Single-Electron Shuttle Based on Electron Spin
- 2014
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Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 112:11
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Tidskriftsartikel (refereegranskat)abstract
- A nanoelectromechanical device based on magnetic exchange forces and electron spin flips induced by a weak external magnetic field is suggested. It is shown that this device can operate as a new type of single-electron "shuttle" in the Coulomb blockade regime of electron transport.
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| 10. |
- Kulinich, Sergeij I., et al.
(författare)
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Umklapp-assisted electron transport oscillations in metal superlattices
- 2012
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Ingår i: Physical Review B. - 1098-0121. ; 85:18, s. artikel nr 184202-
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Tidskriftsartikel (refereegranskat)abstract
- We consider a superlattice of parallel metal tunnel junctions with a spatially nonhomogeneous probability for electrons to tunnel. In such structures tunneling can be accompanied by electron scattering that conserves energy but not momentum. In the special case of a tunneling probability that varies periodically with period a in the longitudinal direction, i.e., perpendicular to the junctions, electron tunneling is accompanied by umklapp scattering, where the longitudinal momentum changes by a multiple of h/a. We predict that as a result a sequence of metal-insulator transitions can be induced by an external electric or magnetic field as the field strength is increased.
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