MgB2超导膜的厚度与其Jc(5K,0T)的关系

通过混合物理化学气相沉积法 (hybrid physical-chemical vapor deposition, HPCVD), 在(000l) SiC 衬底上制得一系列从10 nm到8 μm的MgB₂超导膜样品, 并对它们的形貌、超导转变温度T_c 和临界电流密度J_c与膜厚度的关系进行了研究. 观察到T_c随膜厚度增加上升到最大值后, 尽管膜继续增厚, 但T_c值保持近乎平稳, 而J_c则先随膜厚度增加上升到最高值后, 继而则随膜的厚度的增加而下降. MgB₂膜的T_c(0)和T_c(onset)值与膜厚的关系基本一致, T_c(0)在膜厚为230 nm处达到最大值T_c(0)=41.4 K, 而J_c(5K,0T)在膜厚为100 nm时达到最大值, J_c (5 K, 0 T)=2.3×10⁸A·cm^-2, 这也说明了我们能用HPCVD方法制备出高质量干净MgB₂超导膜. 本文研究的超导膜厚度变化跨度非常大, 从10 nm级的超薄膜到100 nm级的薄膜, 再到几微米的厚膜, 如此T_c和J_c对膜厚度变化的依赖就有了较完整、成体系的研究. 并且本文的工作对MgB₂超导薄膜制备的厚度选取具有实际应用意义. 关键词： 2超导膜')" href="#">MgB₂超导膜 混合物理化学气相沉积法 厚度 临界电流密度

Thickness dependence of critical current density in MgB2 films fabricated by hybrid physical-chemical vapor deposition

MgB₂ superconducting films with a thickness of 10 nm to 8 μ have been prepared on SiC substrates by hybrid physical-chemical vapor deposition (HPCVD). The study on T_c and J_c shows that as the film grows thicker, T_c increases and then keeps stable, which J_c increases at first, and then drops dramatically. We get the maximum T_c at 41.4 K and J_c at 2.3× 10⁸ A·cm^-2. This also shows that we can use the method of HPCVD to prepare high-quality of clean MgB₂ film. And its thickness can be from 10nm ultrathin films and 100 nm thin films up to 8 μm thick film. It is the first time so far as we know that T_c and J_c are studied in this range of thickness. This will lead to a complete and systematical understanding of the superconducting MgB₂ films. And it is also important and practical to choose the thickness when preparing MgB₂ films.
Keywords： 2 superconducting film')" href="#">MgB₂ superconducting film hybrid physical-chemical vapor deposition thickness critical current density