共查询到20条相似文献,搜索用时 15 毫秒
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J. Niemeyer N. D. Kataria M. R. Dietrich C. Politis H. Koch R. Schöllhorn H. Eickenbusch 《Zeitschrift für Physik B Condensed Matter》1987,69(1):1-9
The ac-Josephson effect could be demonstrated up to dc voltages of 20 mV on the I–V characteristic of adjustable YBa2Cu3O7/YBa2Cu3O7 point contacts at 4.2 K. A detailed analysis of the rf power dependence of the size of microwave-induced constant voltage steps is given for microwave frequencies of 70 and 90 GHz. The results prove that electron pairing is responsible for the superconductivity in YBa2Cu3O7. 相似文献
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Shailendra Kumar G Ravikumar P K Mishra P Chaddah B A Dasannacharya Ram Prasad N C Soni 《Pramana》1990,34(4):279-287
We have studied the variation of low field magnetization hysteresis in YBa2Cu3O7 as a function of the maximum magnetic field applied during a hysteresis cycle (1 G<H
max<7.3 G) and also as a function of temperature (77 K<T<95 K). The remnant magnetization is studied as a function ofH
max andT and the measured dependences are explained using the extended critical state model. The potential of this technique as a
contactless method of probing the temperature dependence ofJ
c is discussed. 相似文献
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We have measured the transport critical current densityJ
cof sintered YBa2Cu3O7, in various applied fields up to 185 Oe at 77 K. We find a sharp decay ofJ
cwith magnetic field. We show that this sharp decay is consistent with the low field hysteresis results of Groveret al. We argue that the observed field dependence is not caused by intragranular weak links. 相似文献
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Ayman El Tahan Gerhard Jakob Hermann Adrian Lucica Miu 《Physica C: Superconductivity and its Applications》2010,470(1):1-7
YBa2Cu3O7/PrBa2Cu3O7 (YBCO/PBCO) superlattices with a different ratio of the superconducting and insulating layer thicknesses were prepared by high pressure dc sputtering. The vortex-creep activation energy U0 was determined by analyzing the in-plane resistive transition of 200 μm wide bridges with the external magnetic field B oriented along the c axis. It was found that U0 is proportional to the thickness of the YBCO layers, and does only weakly depend on the PBCO layer thickness, when the latter exceeds two unit cells. We observed a change in the variation of U0 with the current I in the specimen: U0 exhibits a plateau in the low-I region, then decreases significantly with increasing I. This behaviour is explained in terms of a crossover plastic vortex creep – elastic (collective) creep induced by the transport current. 相似文献
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Hiroshi Takahashi Keiko Kato Hidetoshi Nakano Masahiro Kitajima Kenji Ohmori Kazutaka G. Nakamura 《Solid State Communications》2009,149(43-44):1955-1957
Femtosecond time-resolved reflectivity measurement is performed on Y Ba2Cu3O7?δ films. Coherent phonons of both the Ba–O and Cu–O modes are observed at frequencies of 3.4 and 4.3 THz, respectively. Amplitudes of both Ba–O and Cu–O modes are optically manipulated by using a pair of femtosecond pulses, the separation time of which is controlled. Coherent phonons of the Ba–O and Cu–O modes are completely suppressed at the double-pulse separation times of 135.0 and 108.5 fs and those amplitudes are enhanced at 270 and 217 fs, respectively. 相似文献
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