Interaction of hot spots and terahertz waves in Bi2Sr2CaCu2O8 intrinsic Josephson junction stacks of various geometry
Interaction of hot spots and terahertz waves in Bi2Sr2CaCu2O8 intrinsic Josephson junction stacks of various geometry
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DOI：
10.1103/physrevb.82.214506
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发表时间：
2010-12-06
影响因子：
3.7
通讯作者：
Kleiner, R.
中科院分区：
文献类型：
--
作者：
Guenon, S.;Gruenzweig, M.;Kleiner, R.
在足够高的输入功率下，在Bi2Sr2CaCu2O8本征约瑟夫森结的叠层中，热点（加热到超导转变温度以上的区域）与仍处于超导状态的区域共存。在“冷”区，腔共振可以发生，同步交流约瑟夫森电流，并产生强而稳定的相干太赫兹（THz）发射。我们调查的热点和电磁驻波的相互作用，低温扫描激光显微镜和太赫兹发射测量，使用堆栈的各种几何形状。观察到的电磁驻波图案和太赫兹发射的盘形样品。随着输入功率的增加，热点的增长是由一个大的矩形梅萨周围的小检测器结监测。对于两个矩形台面配备了两个电流注入器和一个箭头形的结构，我们表明，驻波可以打开和关闭的堆栈结构的各个区域，这取决于热点位置。结果支持了热点充当由梅萨冷部分形成的腔体的反射终端的观点。
At high enough input power in stacks of Bi2Sr2CaCu2O8 intrinsic Josephson junctions a hot spot (a region heated to above the superconducting transition temperature) coexists with regions being still in the superconducting state. In the "cold" regions cavity resonances can occur, synchronizing the ac Josephson currents and giving rise to strong and stable coherent terahertz (THz) emission. We investigate the interplay of hot spots and standing electromagnetic waves by low-temperature scanning laser microscopy and THz emission measurements, using stacks of various geometries. Standing electromagnetic wave patterns and THz emission are observed for a disk-shaped sample. The growth of a hot spot with increasing input power is monitored by small detector junctions surrounding a large rectangular mesa. For two rectangular mesas equipped with two current injectors and one arrow-shaped structure we show that the standing wave can be turned on and off in various regions of the stack structure, depending on the hot-spot position. The results support the picture of the hot spot acting as a reflective termination of the cavity, formed by the cold part of the mesa.