Dresden 2009 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 32: Postersession Superconductivity: Josephson Junctions, SQUIDs, Heterostructures, Andreev Scattering, Vortex Physics, Cryodetectors, Measuring Devices, Cryotechnique
TT 32.1: Poster
Mittwoch, 25. März 2009, 14:00–18:00, P1A
Investigation of self-heating in Bi2Sr2CaCu2O8 single crystals via low-temperature scanning laser microscopy — •M. Grünzweig1, S. Guénon1, H. B. Wang2, J. Yuan2, A. Iishi2, S. Arisawa2, T. Hatano2, T. Yamashita2, D. Koelle1, and R. Kleiner1 — 1Physikalisches Institut &Center for Collective Quantum Phenomena,Universität Tübingen,Germany — 2National Institute for Materials Science,Tsukuba 3050047, Japan
Recently, relatively strong emission of Terahertz radiation by large stacks of intrinsic Josephson junctions in Bi2Sr2CaCu2O8 single crystals has been discovered [1]. Perhaps surprisingly, the radiation occurs at dc input power levels where Joule heating already changes the temperature distribution in the sample considerably and thus affects the electric properties of the sample. To investigate this we have used low-temperature scanning laser microscopy (LTSLM) to image local electric field distributions in the stacks [2]. For high bias currents we discovered a feature that can be interpreted as a hot spot (i. e. an area of the stack which temperature is above the critical temperature of the superconductor). The fact that the hot spot is accompanied by a standing wave pattern is an indication that the hot spot might play an important role to stimulate Terahertz radiation. We present LTSLM results obtained from stacks with different geometries and with different current injection.
[1] L. Ozyuzer et al., Science 318, 1291 (2007)
[2] H. B. Wang, S. Guénon et al., submitted to Phys. Rev. Lett.;
arXiv:0807.2749v1 [cond-mat.supr-con]