Microwave surface resistance of YBCO superconducting thin films under high DC magnetic field
Microwave surface resistance of YBCO superconducting thin films under high DC magnetic field
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DOI：
10.1016/j.physc.2012.03.035
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发表时间：
2013-01-01
影响因子：
1.7
通讯作者：
Ohshima, S.
中科院分区：
文献类型：
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作者：
Honma, T.;Sato, S.;Ohshima, S.
我们研究了不同厚度的 YBa2Cu3Oy (YBCO) 超导薄膜的微波表面电阻 (R-s) 的直流磁场和温度依赖性。我们使用热共蒸发方法在 MgO (100) 基底上沉积了 300、500 和 700 nm 的 YBCO 薄膜。使用介质谐振器方法在 21.8 GHz 下测量 R-s，并在 R-s 测量过程中平行于 YBCO 薄膜的 c 轴施加高达 12 T 的高直流磁场。当施加直流磁场时，YBCO薄膜的R-s值增加。这些关系可以通过使用高频和低磁场限制的双流体模型来解释。我们将低磁场极限和高磁场极限下的粘性阻力系数eta分别定义为eta(low)(B,T,d)和eta(high)(B,T,d)。 eta（低）值比 eta（高）值大约大两个数量级。此外，随着温度和膜厚度的增加，所有 eta（低）和 eta（高）值都会降低或饱和。这些结果表明，低和高磁场极限下的eta取决于温度和薄膜厚度。 (C) 2012 Elsevier B.V. 保留所有权利。
We investigated the dc magnetic field and temperature dependences of the microwave surface resistance (R-s) of YBa2Cu3Oy (YBCO) superconducting thin films with various thicknesses. We used YBCO thin films with 300, 500, and 700 nm deposited on a MgO (100) substrate by the thermal co-evaporation method. The R-s was measured using the dielectric resonator method at 21.8 GHz, and a high dc magnetic field of up to 12 T was applied parallel to the c-axis of the YBCO thin films during R-s measurements. The R-s value of YBCO thin films increased when dc magnetic field was applied. These relationships could be explained by using the two-fluid model for high frequency and low magnetic field limits. We defined the viscous drag coefficient eta under the low magnetic limit and the high magnetic field limit as the eta(low) (B, T, d) and eta(high) (B, T, d), respectively. The eta(low) values were approximately two orders of magnitude greater than eta(high) values. Also, all eta(low) and eta(high) value decreased or saturated as the temperature and film thickness increased. These results show that eta under the low and high magnetic field limit depended on the temperature and film thickness. (C) 2012 Elsevier B. V. All rights reserved.