Physics / Fizik

Permanent URI for this collectionhttps://hdl.handle.net/11147/6

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Has files: YesInstitution Author: search.filters.institutionAuthor.Kurter, Cihan

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  • Conference Object
    Citation - WoS: 6
    Citation - Scopus: 6
    Fabrication of Array of Mesas on Superconducting Bi2sr 2cacu2o8+? Single Crystals
    (National Institute of Optoelectronics, 2005) Kurter, Cihan; Özyüzer, Lütfi
    The superconducting properties of multi-layered high temperature superconductors (HTS) result mainly from the CuO2 planes, while the other structural components behave simply as charge reservoirs. Using these perfect-layered structures of HTS, arrays of mesas have been fabricated on the surfaces of Bi2Sr2CaCu2O8+δ (Bi2212) single crystals using hotolithography and argon ion beam etching techniques. These arrays have current-voltage (I-V) characteristics that consist of some branches corresponding to different intrinsic Josephson junctions in the mesas, The surface topography and heights of the mesas were examined with atomic force microscopy. Due to the small mesa area, conventional wire bonding techniques are not applicable. A novel method, point contact tunneling apparatus with a sharp Au tip, was used to obtain the I-V characteristics of the fabricated intrinsic Josephson junctions, below the critical temperature of Bi2212. Since the ultimate goal was to obtain an ordered group of mesas with small lateral dimensions, to eliminate heating effects during I-V measurements, we showed that submicron-sized mesas could be characterized by the new technique.
  • Conference Object
    Citation - WoS: 4
    Citation - Scopus: 5
    Comparison of Intrinsic Josephson and Sis Tunneling Spectroscopy of Bi 2sr2cacu2o8+?
    (IEEE, 2005) Özyüzer, Lütfi; Kurter, Cihan; Zasadzinski, John F.; Gray, Kenneth E.; Hinks, David G.; Miyakawa, Nobuaki
    Tunneling spectroscopy measurements are reported on optimally-doped and overdoped Bi2Sr2Ca2Cu2O 8+δ single crystals. A novel point contact method is used to obtain superconductor-insulator-normal metal (SIN) and SIS break junctions as well as intrinsic Josephson junctions (IJJ) from nanoscale crystals. Three junction types are obtained on the same crystal to compare the quasiparticle peaks and higher bias dip/hump structures which have also been found in other surface probes such as scanning tunneling spectroscopy and angle-resolved photoemission spectroscopy. However, our IJJ quasiparticle spectra consistently reveal very sharp conductance peaks and no higher bias dip structures. The IJJ conductance peak voltage divided by the number of junctions in the stack consistently leads to a significant underestimate of Δ when compared to the single junction values. The comparison of the three methods suggests that the markedly different characteristics of IJJ are a consequence of nonequilibrium effects and are not intrinsic quasiparticle features.