Overview
- Discusses the coexistence of the pseudogap and the superconducting gap in the superconducting state.
- Presents the temperature and doping dependencies of the precursor superconducting state
- Investigates the validity of the proposed theories based on the experimental results.
- Nominated as an outstanding contribution by Osaka University's Physics Department in 2013.
- Includes supplementary material: sn.pub/extras
Part of the book series: Springer Theses (Springer Theses)
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Table of contents (5 chapters)
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Front Matter
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Back Matter
Keywords
About this book
In this thesis, the pseudogap and the precursor superconducting state, which are of great importance in clarifying the superconductivity mechanism in high-temperature cuprate superconductors, are investigated with a c-axis optical study in YBa2(Cu1-xZnx)3Oy. Testing was performed over a wide energy range with smaller temperature intervals for several Zn-substituted samples, as well as for several carrier-doping levels.
A spectral weight (SW) analysis, in which the pseudogap behavior can be separated from the superconducting condensate with the SW transfer to the high-energy region, revealed that the pseudogap is not the precursor of the superconductivity (carriers moving to the high-energy region with pseudogap opening never contribute to the superconducting condensation). Moreover, the high-energy transfer continues even below Tc for the Zn-substituted samples (in which we weaken the superconductivity), which gives evidence to the coexistence of the pseudogap and the superconducting gap below Tc.
On the other hand, the analysis of optical conductivity revealed that a precursor state to superconductivity can be defined at temperatures much higher than Tc. The superconducting carrier density (ns) was calculated for each temperature (above and below Tc) and the results confirmed the existence of ns at temperatures above Tc. The observed real superconducting condensate (ns) above Tc puts a serious constraint on the theory for high- Tc superconductivity. A theory based on an inhomogeneous superconducting state, in which a microscopically phase-separated state in a doped Mott insulator can be observed, is the most plausible candidate. This theory can explain the existence of ns and the observedtemperature range for the precursor superconducting state.
The results obtained show that the pseudogap coexists with superconductivity below Tc and is not the precursor of superconductivity. On the other hand, it is also possible to define a precursor superconducting state that is different than the pseudogap. The temperature range and the observed superconducting condensate in this state can be explained with the help of the inhomogeneous superconducting state.
Authors and Affiliations
About the author
Experimental Physics II, Augsburg University, Universitätstrasse 1, D-86159 Augsburg, Germany.
Bibliographic Information
Book Title: Pseudogap and Precursor Superconductivity Study of Zn doped YBCO
Authors: Ece Uykur
Series Title: Springer Theses
DOI: https://doi.org/10.1007/978-4-431-55510-0
Publisher: Springer Tokyo
eBook Packages: Physics and Astronomy, Physics and Astronomy (R0)
Copyright Information: Springer Japan 2015
Hardcover ISBN: 978-4-431-55509-4Published: 23 March 2015
Softcover ISBN: 978-4-431-56271-9Published: 09 October 2016
eBook ISBN: 978-4-431-55510-0Published: 26 February 2015
Series ISSN: 2190-5053
Series E-ISSN: 2190-5061
Edition Number: 1
Number of Pages: XIII, 93
Number of Illustrations: 25 b/w illustrations, 54 illustrations in colour
Topics: Strongly Correlated Systems, Superconductivity, Low Temperature Physics, Magnetism, Magnetic Materials, Solid State Physics, Mathematical Methods in Physics