The Racah Institute of Physics, The Hebrew University of Jerusalem, 91904 Jerusalem, Israel.
J Phys Condens Matter. 2013 Feb 27;25(8):085701. doi: 10.1088/0953-8984/25/8/085701. Epub 2013 Jan 30.
We report results of measurements of the ac conductivity of a Nb superconducting thin film in a swept dc magnetic field. In the mixed state the swept dc field creates vortices at the film surface which pass through the film and form the observed ac conductivity. Vortex rate generation does not depend on the value of the dc field and there is a large plateau-like region of dc magnetic fields where the dissipation is approximately constant. A proposed phenomenological model describes quite well the main features of the ac response in these fields, including its dependency on the sweep rate, ac amplitude, frequency, and value of the second and third harmonics.
我们报告了在扫场直流磁场中测量 Nb 超导薄膜交流电导率的结果。在混合态下，扫场直流磁场在薄膜表面产生涡旋，这些涡旋穿过薄膜并形成观察到的交流电导率。涡旋产生率与直流场的值无关，在直流磁场中有一个大的类平台区域，其中耗散近似恒定。一个提出的唯象模型很好地描述了在这些磁场中交流响应的主要特征，包括它对扫描速率、交流幅度、频率以及第二和第三谐波值的依赖性。
