排序方式: 共有46条查询结果,搜索用时 31 毫秒
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Studies of low-frequency resistance noise show that the dramatic change in the dynamics of the two-dimensional electron system (2DES) in Si that occurs near the metal-insulator transition (MIT) persists in high parallel magnetic fields B such that the 2DES is fully spin polarized. This strongly suggests that charge, as opposed to spin, degrees of freedom are responsible for this effect. In the metallic phase, however, noise is suppressed by a parallel B, pointing to the role of spins. At low B, the temperature dependence of conductivity in the metallic phase provides evidence for a MIT. 相似文献
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S. V. Shitov A. V. Markov B. D. Jackson A. M. Baryshev N. N. Iosad J. -R. Gao T. M. Klapwijk 《Technical Physics》2002,47(9):1152-1157
A quasi-optical mixer containing two Nb/Al/AlOx/Nb superconducting tunnel junctions integrated into a NbTiN/SiO2/Al microstrip line is studied experimentally in the 800–1000 GHz frequency range. The mixer is developed as an optional front end of the heterodyne receiver operating in frequency band 3 or 4 and incorporated into the HIFI module of the Herschel space-borne telescope. The double-dipole antenna of the mixer is made of NbTiN and Al films; the quarter-wavelength reflector, of a Nb film. The mixer is optimized for the IF band of 4–8 GHz. The double-sideband noise temperature T RX measured at 935 GHz is 250 K at a mixer temperature of 2 K and an IF of 1.5 GHz. Within 850–1000 GHz, T RX remains below 350 K. The antenna pattern is symmetrical with a sidelobe level below −16 dB. 相似文献
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The equilibrium critical temperature of a superconducting aluminum strip has been determined with three different methods. The results agree to within 1 mK. By applying microwave radiation superconductivity was maintained up to 57 mK above this critical temperature. These data clearly establish the existense of Tc enhancement. 相似文献
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Shashkin AA Anissimova S Sakr MR Kravchenko SV Dolgopolov VT Klapwijk TM 《Physical review letters》2006,96(3):036403
Thermodynamic measurements reveal that the Pauli spin susceptibility of strongly correlated two-dimensional electrons in silicon grows critically at low electron densities--behavior that is characteristic of the existence of a phase transition. 相似文献
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Franck S. Schoonbeek Jan H. van Esch Bas Wegewijs Diederik B. A. Rep Matthijs P. de Haas Teun M. Klapwijk Richard M. Kellogg Ben L. Feringa 《Angewandte Chemie (International ed. in English)》1999,38(10):1393-1397
Hydrogen bonds between urea units allow self-organization of π systems in mono- and bithiophenes into fibers as shown schematically. In these fibers there is a surprisingly high mobility of charge carriers as determined by pulse-radiolysis time-resolved microwave conductivity measurements. 相似文献
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