Surface resistance and nonlinear dynamic microwave losses of epitaxial HTS films
Surface resistance and nonlinear dynamic microwave losses of epitaxial HTS films
复制标题
外延高温超导薄膜的表面电阻和非线性动态微波损耗
DOI：
--
复制
发表时间：
1997
影响因子：
1.8
通讯作者：
H. Schlick
中科院分区：
文献类型：
--
作者：
W. Diete;M. Getta;M. Hein;T. Kaiser;G. Muller;H. Piel;H. Schlick
高温超导体（HTS）薄膜在微波器件中的许多应用都需要高功率处理能力。因此，我们利用非常灵敏的介电谐振器技术研究了19GHz下无图像化高温超导薄膜表面电阻R/sub s/(T,B/sub s/)与温度和功率的关系。在4.2和77K下，YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// (Tl/sub 2/Ba/sub 2/Ca/sub 1/Cu/sub 2/O/sub 8/)薄膜的R/sub s/-值低至120/spl plusmn/15 /spl mu//spl Omega/ (100/spl plusmn/15 /spl mu//spl Omega/)和760/spl plusmn/80 /spl mu//spl Omega/ (610/spl plusmn/30 /spl mu//spl Omega/)。相对于低场R/sub s/的小散射，高场行为变化强烈。在77K （4.2K）时，表面磁场（B/sub /s /）在1 ~ 15 mT （2 ~ 28 mT）之间。可以确定不同的损耗机制，如缺陷、加热和内在现象。除了脉冲模式下的时域测量外，还通过双音互调测量研究了非线性的动态性质。该技术的高灵敏度被用于证明高质量薄膜中存在快速非线性（t<100 ps）。
Many applications of high-temperature superconductor (HTS) films in microwave devices require high power-handling capabilities. Therefore we have studied the temperature and power dependence of the surface resistance R/sub s/(T,B/sub s/) of unpatterned HTS films with a very sensitive dielectric resonator technique at 19GHz. R/sub s/-values as low as 120/spl plusmn/15 /spl mu//spl Omega/ (100/spl plusmn/15 /spl mu//spl Omega/) and 760/spl plusmn/80 /spl mu//spl Omega/ (610/spl plusmn/30 /spl mu//spl Omega/) at 4.2 and 77K were obtained for YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// (Tl/sub 2/Ba/sub 2/Ca/sub 1/Cu/sub 2/O/sub 8/) films. In contrast to the small scattering in R/sub s/ at low fields, the high-field behavior varied strongly. Maximum surface magnetic fields (B/sub s/) between 1 and 15 mT (2-28 mT) were achieved at 77K (4.2K). Different loss mechanisms, like defects, heating, and intrinsic phenomena, could be identified. Besides time-domain measurements in the pulsed mode, the dynamic nature of the nonlinearities was investigated by two-tone intermodulation measurements. The very high sensitivity of this technique was applied to proof the existence of fast nonlinearities (t<100 ps) in high quality films.