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R. Arce L. Civale J. Luzuriaga J. Guimpel F. de la Cruz 《Solid State Communications》1983,48(12):1027-1030
Penetration depth measurements show that thermal heat treatment in amorphous Zr70Cu30 induces a normal region 5000 Å thick at the surface of ultrarapid quenched ribbons. Upper critical field measurements indicate that the new induced phase is a normal one while the rest of the sample remains as a homogeneous superconducting phase. 相似文献
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J.R. Thompson Yang Ren Sun D.K. Christen L. Civale A.D. Marwick F. Holtzberg 《Physica A》1993,200(1-4):395-402
Studies of vortex dynamics and pinning were conducted in irradiated Y1Ba2Cu3O7 single crystals by observing the decay of supercurrents with time. The materials contained either point-like defects from proton irradiation or line-like defects from irradiation with energetic heavy ions. Analysis of the first case gives clear support for collective creep theory. With linear defects, the experiments give evidence for thermal smearing of the vortex pinning potential at higher temperatures, as predicted theoretically. 相似文献
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Luo HM Jain M Baily SA McCleskey TM Burrell AK Bauer E DePaula RF Dowden PC Civale L Jia QX 《The journal of physical chemistry. B》2007,111(26):7497-7500
Epitaxial ferromagnetic SrRuO3 thin films with a room-temperature resistivity of 300 microOmega.cm have been successfully grown on LaAlO3(001) substrates at a processing temperature in the range of 550-750 degrees C by a polymer-assisted deposition technique. X-ray diffraction analysis shows good epitaxial quality of SrRuO3 thin films, giving values of the full width at half-maximum (FWHM) of 0.42 degrees from the rocking curve for the (002) reflection and 1.1 degrees from the in-plane phi scan for the (204) reflection. Both the resistivity and the magnetization versus temperature measurements show that the SrRuO3 films are ferromagnetic with a transition temperature of 160 K. The spontaneous magnetization near the ferromagnetic transition follows the scaling law, and the low-temperature magnetization follows the Bloch law. 相似文献
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H. Wang S.R. Foltyn L. Civale B. Maiorov Q.X. Jia 《Physica C: Superconductivity and its Applications》2009,469(23-24):2033-2036
Numerous experimental results have suggested that the Jc of YBa2Cu3O7 (YBCO) films is significantly higher near the film–substrate interface than in the remainder of the film. We previously proposed that this effect is due to interfacial pinning enhancement caused by stress and the resulting misfit dislocations at the heteroepitaxial interface. To test this hypothesis we have used a non-superconducting PrBa2Cu3O7?δ (PrBCO) buffer layer to minimize the lattice mismatch with YBCO. We find that the PrBCO layers lower Jc of the 0.4 μm YBCO films in a predictable way, and that, if sufficiently thick (~0.5 μm), they eliminate interfacial enhancement altogether. Our interpretation of this result is that the defects responsible for interfacial enhancement of flux pinning originate at the bottom of the non-superconducting PrBCO layer, which screens the pinning centers from vortices in YBCO. This result demonstrates that the pinning enhancement arises from stress at the film–substrate interface. 相似文献
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An abrupt collapse of the irreversibility line is observed in both twinned and untwinned YBaCuO crystals within a critical regime. The exponent of the power law describing the irreversibility line Hirr changes from
at high fields to larger values (between 1.5 and 2) below the collapse. We propose that the observed low field anomaly, which extends down to temperatures well below the irreversibility line, is associated with the thermal softening boundary which increases as T2 and crosses Hirr shifting it to lower fields. Below this crossover, which occurs when the mean-square thermal displacement √ u2 of the vortices exceeds coherence length ξ, the strength of the pinning is strongly reduced. 相似文献
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Zhang Y Haberkorn N Ronning F Wang H Mara NA Zhuo M Chen L Lee JH Blackmore KJ Bauer E Burrell AK McCleskey TM Hawley ME Schulze RK Civale L Tajima T Jia Q 《Journal of the American Chemical Society》2011,133(51):20735-20737
The synthesis of pure δ-MoN with desired superconducting properties usually requires extreme conditions, such as high temperature and high pressure, which hinders its fundamental studies and applications. Herein, by using a chemical solution method, epitaxial δ-MoN thin films have been grown on c-cut Al(2)O(3) substrates at a temperature lower than 900 °C and an ambient pressure. The films are phase pure and show a T(c) of 13.0 K with a sharp transition. In addition, the films show a high critical field and excellent current carrying capabilities, which further prove the superior quality of these chemically prepared epitaxial thin films. 相似文献