共查询到18条相似文献,搜索用时 93 毫秒
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现代可编程约瑟夫森电压基准的核心器件是约瑟夫森结阵.目前最具有优势的约瑟夫森结阵是 Nb/NbxSi1-x/Nb材料的结阵. Nb/NbxSi1-x/Nb材料的约瑟夫森结 具有三层薄膜的制作过程简便, Nb和NbxSi1-x刻蚀工艺相同以及NbxSi1-x 势垒层成分可调等优点.中国计量科学研究院设计制作了Nb/NbxSi1-x/Nb约瑟夫森单结. 通过在4.2 K低温下对所做单结进行直流电流-电压特性测量,观测到了清晰的超导隧穿电流和 从零电压态向电压态的跳变,最后就测量结果进行了分析讨论.此项工作属于国内首个开展 Nb/NbxSi1-x/Nb材料约瑟夫森单结研究的工作. 相似文献
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采用基于第一性原理的平面波赝势方法,研究了Nb原子在Ni3Al中的格点取代行为及合金化效应.通过对不同原子被置换后体系的形成热、结合能及电子态密度的计算和比较,发现Nb原子倾向于取代Ni3Al中的Al原子,其取代行为主要由系统的电子结构决定,计算结果与实验相符.为了进一步研究Nb原子的取代行为,对Nb原子占据的格点以松散或紧凑分布下体系的总能、形成热、结合能以及电子态密度进行了计算,结果表明Nb原子占据的格点更倾向于紧凑分布.为了研究Nb对Ni3关键词:
第一性原理
3Al合金')" href="#">Ni3Al合金
电子结构
合金化效应 相似文献
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用溶胶-凝胶旋涂法在玻璃基底上制备出Nb/SnO2复合透明导电薄膜,利用XRD,SEM,紫外—可见分光光度计,四探针电阻仪等测试方法对Nb/SnO2复合薄膜的结构和物性进行了研究.结果表明: 当Nb含量小于0.99at%时,Nb/SnO2复合薄膜为较纯的四方金红石结构;复合薄膜中晶粒分布均匀,平均尺寸在5—7 nm.当Nb含量小于0.99at%时,Nb/SnO2复合薄膜的电阻率先减小后增大,当Nb含量为0.37at%时
关键词:
溶胶-凝胶法
2复合薄膜')" href="#">Nb/SnO2复合薄膜
结构表征
光电性能 相似文献
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Nb/Al-AlOx/Nb tunnel junctions with controllable critical current density Jc are fabricated using the standard selective Nb etching process.Tunnel barriers are formed in different oxygen exposure conditions (oxygen pressure P and oxidation time t),giving rise to Jc ranging from 100 A/cm2 to above 2000 A/cm2.Jc shows a familiar linear dependence on P × t in logarithmic scales.We calculate the energy levels of the phaseand flux-type qubits using the achievable junction parameters and show that the fabricated Nb/Al-AlOx/Nb tunnel junctions can be used conveniently for quantum computation applications in the future. 相似文献
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Band structure in the conductivity of 4-barrier Nb/Al-AlOx-Al-AlOx-Al-AlOx-Al-AlOx-Nb (SINININIS) tunnel junctions is observed at low temperatures. This structure is explained in terms of the interference of quasiparticle waves in a periodic barrier. 相似文献
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I. P. Nevirkovets 《Czechoslovak Journal of Physics》1996,46(Z2):647-648
Modified geometry (MG) devices, Nb/Al/Nb/Al−AlOx−Al−AlOx−Al/Nb/Al/Nb, have been fabricated and investigated in comparison with the basic geometry (BG) double-barrier Nb/Al−AlOx−Al−AlOx−Al/Nb devices. The enhancement of the critical temperature in the Al film is found to be weaker for the MG devices as compared
with the BG devices at temperatures nearT=4.2 K but stronger at lowT. Indication of an enhancement of dc Josephson critical current density,j
c
, at bias voltageV≠0 as compared withj
c
(V=0) has been observed in the MG devices for the first time. 相似文献
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M. Schöck C. Sürgers H. v. Löhneysen 《The European Physical Journal B - Condensed Matter and Complex Systems》2000,14(1):1-10
The superconducting and magnetic properties of Nb/Pd1-xFex/Nb triple layers with constant Nb layer thickness dNb=200 ? and different interlayer thicknesses 3 ?≤ dPdFe ≤ ? are investigated. The thickness dependence of the magnetization and of the superconducting transition temperature shows
that for small iron concentration x the Pd1-xFex layer is likely to be in the paramagnetic state for very thin films whereas ferromagnetic order is established for x ≥ 0.13.
The parallel critical field Bc2||(T){B_{c2||}}(T) exhibits a transition from two-dimensional (2D) behavior where the Nb films are coupled across the interlayer, towards a
2D behavior of decoupled Nb films with increasing dPdFeand/or x. This transition allows a determination of the penetration depth xF{\xi _F} of Cooper pairs into the Pd1-xFex layer as a function of x. For samples with a ferromagnetic interlayer xF{\xi _F} is found to be independent of x. 相似文献
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J. W. Kooi M. Chan B. Bumble H. G. LeDuc P. Schaffer T. G. Phillips 《International Journal of Infrared and Millimeter Waves》1995,16(12):2049-2068
We report results on two full height waveguide receivers that cover the 200–290 GHz and 380–510 GHz atmospheric windows. The receivers are part of the facility instrumentation at the Caltech Submillimeter Observatory on Mauna Kea in Hawaii. We have measured receiver noise temperatures in the range of 20K–35K DSB in the 200–290 GHz band, and 65–90K DSB in the 390–510 GHz atmospheric band. In both instances low mixer noise temperatures and very high quantum efficiency have been achieved. Conversion gain (3 dB) is possible with the 230 GHz receiver, however lowest noise and most stable operation is achieved with unity conversion gain.A 40% operating bandwidth is achieved by using a RF compensated junction mounted in a two-tuner full height waveguide mixer block. The tuned Nb/AlO
x
/Nb tunnel junctions incorporate an end-loaded tuning stub with two quarter-wave transformer sections to tune out the large junction capacitance. Both 230 and 492 GHz SIS junctions are 0.49µm2 in size and have current densities of 8 and 10 kA/cm2 respectively.Fourier Transform Spectrometer (FTS) measurements of the 230 and 492 GHz tuned junctions show good agreement with the measured heterodyne waveguide response. 相似文献
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I.P. Nevirkovets O. Chernyashevskyy C. Petrovic Rongwei Hu J.B. Ketterson Bimal K. Sarma 《Physica C: Superconductivity and its Applications》2009,469(7-8):293-296
We report characteristics of CeCoIn5/Al/AlOx/Nb and CeCoIn5/Al/AlOx/Al tunnel junctions fabricated on the (0 0 1) surface of CeCoIn5 crystal platelets. The main result of this work is the observation of a low Josephson current (as compared with that expected from the Ambegaokar–Baratoff formula), which is consistent with idea that the order parameter in the heavy-fermion superconductor CeCoIn5 has unconventional pairing symmetry. 相似文献
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P. Febvre W. R. McGrath P. Batelaan B. Bumble H. G. LeDuc S. George P. Feautrier 《International Journal of Infrared and Millimeter Waves》1994,15(6):943-965
A heterodyne receiver using an SIS waveguide mixer with two mechanical tuners has been characterized from 480 GHz to 650 GHz. The mixer uses either a single 0.5 × 0.5 µm2 Nb/AlOx/Nb SIS tunnel junction or a series array of two 1 µm2 Nb tunnel junctions. These junctions have a high current density, in the range 8 – 13 kA/cm2. Superconductive RF circuits are employed to tune the junction capacitance. DSB receiver noise temperatures as low as 200 ± 17 K at 540 GHz, 271 K ± 22 K at 572 GHz and 362 ± 33 K at 626 GHz have been obtained with the single SIS junctions. The series arrays gave DSB receiver noise temperatures as low as 328 ± 26 K at 490 GHz and 336 ± 25 K at 545 GHz. A comparison of the performances of series arrays and single junctions is presented. In addition, negative differential resistance has been observed in the DC I–V curve near 490, 545 and 570 GHz. Correlations between the frequencies for minimum noise temperature, negative differential resistance, and tuning circuit resonances are found. A detailed model to calculate the properties of the tuning circuits is discussed, and the junction capacitance as well as the London penetration depth of niobium are determined by fitting the model to the measured circuit resonances. 相似文献
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Jinzhong Zhang Abdur Rehman Jalil Pok-Lam Tse Jonas Kölzer Daniel Rosenbach Helen Valencia Martina Luysberg Martin Mikulics Gregory Panaitov Detlev Grützmacher Zhigao Hu Jia Grace Lu Thomas Schäpers 《Annalen der Physik》2020,532(8):2000273
Nanohybrid superconducting junctions using antimony telluride (Sb2Te3) topological insulator nanoribbons and Nb superconducting electrodes are fabricated using electron beam lithography and magnetron sputtering. The effects of bias current, temperature, and magnetic field on the transport properties of the junctions in a four-terminal measurement configuration are investigated. Two features are observed. First, the formation of a Josephson weak-link junction. The junction is formed by proximity-induced areas in the nanoribbon right underneath the inner Nb electrodes which are connected by the few tens of nanometers short Sb2Te3 bridge. At 0.5 K a critical current of 0.15 µA is observed. The decrease of the supercurrent with temperature is explained in the framework of a diffusive junction. Furthermore, the Josephson supercurrent is found to decrease monotonously with the magnetic field indicating that the structure is in the small-junction limit. As a second feature, a transition is also observed in the differential resistance at larger bias currents and larger magnetic fields, which is attributed to the suppression of the proximity-induced superconductive state in the nanoribbon area underneath the Nb electrodes. 相似文献