Topic
High-temperature superconductivity
About: High-temperature superconductivity is a research topic. Over the lifetime, 7263 publications have been published within this topic receiving 175377 citations. The topic is also known as: high-temperature superconductivity.
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TL;DR: In this article, the authors reported the growth of single crystals as large as 4 mm of YBa2Cu3O7 and DyBa2C 3O 7 and confirmed superconductivity in them by magnetic and electrical measurements.
Abstract: Increased understanding of fundamental properties of the new cuprate superconductors depends on advances in the preparation of quality materials for study. Early work focused on the study of sintered polycrystalline samples. In some cases, grain growth during sintering yielded individual grains large enough (˜80 μm) for single crystal X-ray determination1. Larger single crystals allow measurements of physical properties including measurements of anisotropic behaviour. The anisotropy of upper critical fields in YBa2Cu3O7 single crystals has been reported by lye et al.2 who found critical fields characteristic of a quasi-two-dimensional superconductor, which are highest when the field is orientated perpendicular to the c-axis. Dinger et al.3 have measured critical fields and critical currents of single crystals and find anisotropies of 10 and greater3. These studies contain little detail on the crystal growth of YBa2Cu3O7. Here we report the growth of single crystals as large as 4 mm of YBa2Cu3O7 and DyBa2Cu3O7 and confirm superconductivity in them by magnetic and electrical measurements. Single crystals of other rare earth barium cuprates are also obtained although we have yet to optimize growth conditions for these phases.
265 citations
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13 Feb 1997TL;DR: In this paper, the surface impedance of HTS materials is investigated and some useful relations for superconductivity at microwave frequencies are discussed, as well as the relationship between HTS material surface impedance and superconducting delay lines.
Abstract: Preface Acknowledgements 1. Superconductivity at microwave frequencies 2. Superconducting transmission lines 3. Superconducting cavity resonators 4. Microwave measurements 5. Superconducting filters 6. Superconducting delay lines 7. Superconducting antennas 8. Signal processing systems Appendix 1: The surface impedance of HTS materials Appendix 2: Substrates for superconductors Appendix 3: Some useful relations Index.
258 citations
TL;DR: In this paper, it was shown that the clean, low-temperature phase of 6-8% electron-doped Sr2IrO4 has gapless excitations only at four isolated points in the Brillouin zone, with a predominant d-wave symmetry of the gap.
Abstract: Sr2IrO4 bears a striking electronic resemblance to the cuprate superconductors, except the iridate is an insulator. Introducing electrons into Sr2IrO4 leads to a d-wave gap, suggesting superconductivity or something equally exotic. High-temperature superconductivity in cuprates emerges out of a highly enigmatic ‘pseudogap’ metal phase. The mechanism of high-temperature superconductivity is probably encrypted in the elusive relationship between the two phases, which spectroscopically is manifested as Fermi arcs—disconnected segments of zero-energy states—collapsing into d-wave point nodes upon entering the superconducting phase. Here, we reproduce this distinct cuprate phenomenology in the 5d transition-metal oxide Sr2IrO4. Using angle-resolved photoemission, we show that the clean, low-temperature phase of 6–8% electron-doped Sr2IrO4 has gapless excitations only at four isolated points in the Brillouin zone, with a predominant d-wave symmetry of the gap. Our work thus establishes a connection between the low-temperature d-wave instability and the previously reported high-temperature Fermi arcs in electron-doped Sr2IrO4 (ref. 1). Although the physical origin of the d-wave gap remains to be understood, Sr2IrO4 is the first non-cuprate material to spectroscopically reproduce the complete phenomenology of the cuprates, thus offering a new material platform to investigate the relationship between the pseudogap and the d-wave gap.
258 citations
TL;DR: In this paper, the authors show experimental evidence that flux motion results from a thermally activated crossover from 3D vortex lines to 2D independent pancake-like vortices in the Cu-O layers, which occurs when kBT exceeds the Josephson coupling energy of these layers.
Abstract: For H‖c-axis, the magnetic field induced broadening of the resistive transitions of high-Tc superconductors (HTS) is shown to depend strongly on the Cu-O layer spacing. For the highly anisotropic HTS, we show experimental evidence that flux motion results from a thermally activated crossover from three dimensional (3D) vortex lines to 2D independent pancake-like vortices in the Cu-O layers, which is intrinsic to the material and occurs when kBT exceeds the Josephson coupling energy of these layers. At low temperatures, however, thermally activated conventional depinning (which can be sample dependent) or melting in the uncoupled 2D Cu-O layers is also required for flux motion. For YBa2Cu3O7, this dimensional crossover does not occur belowHc2, presumably because the conducting Cu-O chains short-circuit the Josephson interlayer coupling, leading to better superconducting properties in a magnetic field. These results show that strong interlayer coupling is a key to finding good alternatives.
257 citations
TL;DR: In this paper, a broad superconducting transition with an onset near 30 K was observed for La-Ba-Cu oxides in the measurement of magnetic susceptibility, which is of bulk nature and reproducible after several heat cycles.
Abstract: A broad superconducting transition with an onset near 30 K is observed for La-Ba-Cu oxides in the measurement of magnetic susceptibility. The superconductivity is of bulk nature and reproducible after several heat cycles.
257 citations