Preparation, characterization, and far-infrared study of ceramic high-Tc superconductors

Zetterer, T.; Ose, W.; Schützmann, J.; Otto, H. H.; Obermayer, P. E.; Tasler, N.; Lengfellner, Hans; Lugert, G.; Keller, J.; Renk, K. F.

doi:10.1364/josab.6.000420

Cited by 19 publications

(4 citation statements)

References 45 publications

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“…In fact, the relevant infrared active modes are expected and observed in the frequency range of the subgap structures. 74,75 However, the discrepancies between the different sources are considerably higher than the mutual deviation of our experimental data for all samples investigated.…”

Section: ͑23͒mentioning

confidence: 55%

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Tunneling spectroscopy with intrinsic Josephson junctions inBi2Sr2CaCu

et al. 1998

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The paper presents a detailed discussion of the current-voltage characteristic of intrinsic Josephson junctions in Bi 2 Sr 2 CaCu 2 O 8ϩ␦ and Tl 2 Ba 2 Ca 2 Cu 3 O 10ϩ␦ . In these materials Josephson tunnel junctions are formed naturally between adjacent superconducting CuO 2 bilayers or trilayers. A typical sample consists of a stack of Josephson junctions. We explicitly show that all junctions inside a given sample have identical tunneling characteristics. We discuss the shape ͑general curvature͒ of the current-voltage characteristic in terms of a superconducting order parameter that has a predominant d x 2 Ϫy 2 symmetry. The I c R n product of the intrinsic Josephson junctions turns out to be 2-3 mV, about 10% of the maximum energy gap ⌬ 0 /e. The currentvoltage characteristic of every individual junction exhibits pronounced structures in the subgap regime. They are best explained by a recently proposed resonant coupling mechanism between infrared active optical c-axis phonons and oscillating Josephson currents.

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Section: ͑23͒mentioning

confidence: 55%

“…74͒ and TBCCO. 75 The ͑average͒ electric field in the junction polarizes the ions of charge q in the barrier. This is illustrated on the right side of Fig.…”

Section: H Discussion Of the Subgap Structuresmentioning

confidence: 99%

Tunneling spectroscopy with intrinsic Josephson junctions inBi2Sr2CaCu

et al. 1998

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“…The bond distances and force constants [14][15][16][17] for YbBa 2 Cu 3 O 7 are given in Table 1. Table 2 gives shell parameters of the model for YbBa 2 Cu 3 O 7 along with Born-Mayer constants.…”

Section: Resultsmentioning

confidence: 99%

“…Bond distances (A) and force constants[14][15][16][17] for YbBa 2 Cu 3 O 7 (in units of 10 −12 Nm −1 for stretching and 10 −18 Nm rad −2 for bending)…”

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confidence: 99%

Phonon Frequency Spectrum HTSC YbBa2Cu3O7

Mohan

Jose

Abiy

2012

J Supercond Nov Magn

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Since the discovery of the high T c superconductivity by Bednorz and Muller, several workers around the world have studied several systems to reach a really high T c superconductor. As the strong electron-phonon coupling may be one of the possible origins of the high T c , a knowledge about the phonon in these materials is essential. In order to investigate phonon spectra, one has to study Raman and infrared spectra of these systems. But there is a little information about the Raman spectra and infrared absorption spectra are available in the literature. Hence, a theoretical evaluation of phonon frequencies of high temperature superconductors assume importance. Due to strong covalent bonding nature in high temperature superconductors, a normal coordinate analysis using Wilson's FG matrix is applied to evaluate Phonon frequencies. The normal coordinate analysis of optically active lattice vibrations will be useful for the theoretical interpretation of vibrational spectrum at the center of Brillouin zone in high T c superconductors. Hence, an attempt is made to evaluate all the phonon frequencies of HTSC YbBa 2 Cu 3 O 7 through normal coordinate analysis. Calculations of lattice dynamics is also performed by use of the modified three body force shell model. The present approach leads to a better understanding of phonon frequency of high T c superconductor YbBa 2 Cu 3 O 7 under investigations in the present work. This calculations yield not only the zone center phonon modes but also the stable dispersion curves through out the Brillouin zone. It also supports strong electron-phonon interactions in high T c superconductors.

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