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arXiv 0810.5268cond-mat.supr-con
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本征约瑟夫森结的太赫兹电磁波发射机制

Mechanism of Terahertz Electromagnetic Wave Emission from Intrinsic Josephson Junctions

Masashi Tachiki, Shouta Fukuya, Tomio Koyama

摘要:

利用三维平行六面体模型计算了本征约瑟夫森结在外加电流作用下的约瑟夫森等离子体波的腔共振模。激发的约瑟夫森等离子体的电磁(EM)波在样品表面被转换为THz EM波。超导体序参量的静态相位扭折所伴随的腔模已被深入研究。相位扭折引起了扭折附近序参量振幅的空间调制,降低了超导凝聚能。约瑟夫森等离子体在真空中除了发射EM波之外还产生磁场。这种磁能决定了腔模的方向。考虑到上述事实,我们得到了尖锐的共振峰的I-V曲线和相当大的功率的连续和相干太赫兹波发射的腔共振。发射频率与样品短边的长度成反比,与实验结果一致。

英文摘要:

Using a 3-D parallelepiped model of intrinsic Josephson junctions, we calculate the cavity resonance modes of Josephson plasma waves excited by external electric currents. The electromagnetic (EM) wave of the excited Josephson plasma is converted to a THz EM wave at the sample surfaces. The cavity modes accompanied by static phase kinks of the superconducting order parameter have been intensively investigated. The phase kinks induce a spatial modulation of the amplitude of the order parameter around the kinks and decrease the superconducting condensation energy. The Josephson plasma produces a magnetic field in the vacuum in addition to the emitted EM wave. This magnetic energy detemines the orientation of the cavity mode. Taking account of the facts mentioned above, we obtained sharp resonance peaks in the I-V curves and sizable powers of continuous and coherent terahertz wave emission at the cavity resonance. The emission frequencies are inversely proportional to the length of the shorter side of the samples in agreement with experiments.

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