Department of Physics, University of Central Florida, Orlando, FL 32816, USA.
J Phys Condens Matter. 2011 Jan 19;23(2):025701. doi: 10.1088/0953-8984/23/2/025701. Epub 2010 Dec 16.
We re-examined the angular dependence of the radiation from the intrinsic Josephson junctions in rectangular mesas of Bi(2)Sr(2)CaCu(2)O(8 + δ), in order to determine if the cavity mode part of the radiation arises from waves across the width w or along the length l of the mesas, associated with 'hot spots' (Wang et al 2010 Phys. Rev. Lett. 105 057002). We derived analytical forms for the angular dependence expected in both cases for a general cavity mode in which the width of the mesa corresponds to an integer multiple of one-half the wavelength of the radiation. Assuming the coherent radiation from the ac Josephson current source and the cavity magnetic surface current density source combine incoherently, fits to the data of Kadowaki et al (2010 J. Phys. Soc. Japan 79 023703) on a mesa with mean l/ω = 5.17 for both wave directions using two models for the incoherent combination were made, which correspond to standing and traveling waves, respectively. The results suggest that the combined output from the uniform ac Josephson current source plus a cavity wave forming along the rectangle length is equally probable as that of the combined output from the uniform ac Josephson current plus a cavity wave across the width. However, for mesas in which nl/2ω is integral, where n is the index of the rectangular TM(z)(n, 0) mode, it is shown that standing cavity mode waves along the length of the mesa do not radiate in the xz plane perpendicular to the length of the mesa, suggesting experiments on such mesas could help to resolve the question.
我们重新研究了 Bi(2)Sr(2)CaCu(2)O(8 + δ) 矩形台面中本征约瑟夫森结的辐射角依赖性，以确定辐射的腔模部分是来自横跨台面宽度 w 还是沿长度 l 的波，与“热点”有关（Wang 等人，2010 年，Phys. Rev. Lett. 105，057002）。我们为一般腔模推导了在这两种情况下的角依赖性的解析形式，其中台面的宽度对应于辐射的半波长的整数倍。假设来自 ac 约瑟夫森电流源的相干辐射和腔磁面电流密度源的相干辐射在数据中是不相干的，对于 Kadowaki 等人（2010 年，J. Phys. Soc. Japan 79，023703）在两个波方向上的平均 l/ω=5.17 的台面数据，使用两种不相干组合模型进行了拟合，分别对应于驻波和行波。结果表明，来自均匀 ac 约瑟夫森电流源加上沿矩形长度形成的腔波的组合输出与来自均匀 ac 约瑟夫森电流源加上横跨宽度的腔波的组合输出同样可能。然而，对于 nl/2ω 是整数的台面，其中 n 是矩形 TM(z)(n, 0)模式的指数，表明沿台面长度的驻腔模波不会在垂直于台面长度的 xz 平面中辐射，这表明对这种台面的实验可能有助于解决这个问题。
