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首页> 外文期刊>Journal of Applied Physics >Preparation, tunneling, resistivity, and critical current measurements on homogeneous highTc A15 Nb3Ge thin films
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Preparation, tunneling, resistivity, and critical current measurements on homogeneous highTc A15 Nb3Ge thin films

机译：在均质高Tc A15 Nb3Ge薄膜上的制备，隧穿，电阻率和临界电流测量

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We have prepared homogeneous films of high Tc Nb3Ge as demonstrated by a total transition width of less than 1 K with a resistive Tc onset of 21.7 K, by paying particular attention to the constancy of substrate temperature. Xray diffraction analysis done both at Stanford and at Westinghouse shows no evidence of a second phase to the limits of the instruments (≪1%). Tunneling as a function of thickness shows the material to be of good quality (high, sharp gaps; low excess conductance below the sum gap) at the surface for thicknesses of up to 1 μm and only slightly degraded at 5 μm. Further evidence of homogeneity is demonstrated by critical current measurements which give an extrapolated T c of 20 K on material with resistive Tc onset of 21.9 K. Critical current densities at 14 K in a 0.5 T field are as high as 9×106 A/cm2, which are the highest ever reported for any material at this temperature. In an applied magnetic field of 7.5 tesla, Jc was 2.5×106 A/cm2 at 4.2 K. Tunneling as a function of thickness into Nb3Ge where the oxygen had been removed from the system after 1300 Å had been deposited but the deposition continued up to 1 μm showed only limited degradation (in terms of gap width, excess conductance below the gap as well as magnitude of gap). This gives some indication that oxygen may only be needed initially during the deposition rather than throughout the entire deposition. Tc correlates well with composition, as does resistivity, thus we see the correlation between increasing Tc and decreasing resistivity.
机译：通过特别注意基板温度的恒定性，我们制备了高Tc Nb3Ge的均质膜，其总过渡宽度小于1 K，电阻Tc起始值为21.7K。在斯坦福大学和西屋大学进行的X射线衍射分析表明，没有证据表明第二阶段达到了仪器的极限（≪1％）。随厚度变化的隧穿表明，材料的表面质量好（高，尖锐的间隙；低于总间隙的过剩电导率低），厚度最大为1μm，在5μm处仅发生轻微降解。临界电流测量证明了同质性的进一步证据，在电阻Tc开始为21.9 K的材料上，外推的T c为20K。0.5T场中14 K的临界电流密度高达9×106 A / cm2 ，这是该温度下所有材料中报道的最高值。在7.5 tesla的外加磁场中，Jc在4.2 K下为2.5×106 A / cm2。随厚度的增加隧穿到Nb3Ge中，在该处沉积了1300Å后已从系统中除去了氧气，但沉积持续到1μm仅显示有限的退化（就间隙宽度，间隙以下的过剩电导以及间隙的大小而言）。这表明在沉积过程中最初可能只需要氧气，而不是整个沉积过程中都需要氧气。 Tc与成分之间的相关性很好，电阻率也是如此，因此我们看到Tc的增加与电阻率的降低之间的相关性。

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    《Journal of Applied Physics》 |1982年第12期|P.8907-8914|共8页
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  • 收录信息 美国《科学引文索引》(SCI);美国《工程索引》(EI);美国《生物学医学文摘》(MEDLINE);
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