Interaction of hot spots and terahertz waves in Bi2 Sr 2 CaCu2 O8 intrinsic Josephson junction stacks of various geometry

S. Guénon*, M. Grünzweig, B. Gross, J. Yuan, Z. G. Jiang, Y. Y. Zhong, M. Y. Li, A. Iishi, P. H. Wu, T. Hatano, R. G. Mints, E. Goldobin, D. Koelle, H. B. Wang, R. Kleiner

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

At high enough input power in stacks of Bi2 Sr2 CaCu2 O8 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.

Original languageEnglish
Article number214506
JournalPhysical Review B - Condensed Matter and Materials Physics
Volume82
Issue number21
DOIs
StatePublished - 6 Dec 2010

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