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A detailed doping survey of the low-energy electrodynamics of YBa2Cu3O6+x Baglo, Jordan Carl
Abstract
The rich phenomenology displayed by the high temperature (high-Tc) cuprate superconductors has attracted intense experimental and theoretical attention for nearly thirty years. Despite steady and continued progress, a complete and consistent microscopic theory of the cuprates continues to elude researchers. However, recent work appears to be converging on a picture of separate spin and charge order phase transitions – well below and slightly above optimal doping, respectively – along with associated Fermi surface reconstruction. As sensitive probes of the low-energy electrodynamics, microwave conductivity techniques are well-suited for characterizing the effects of such changes in electronic structure. For YBa₂Cu₃0₆₊x (YBCO), one of the cleanest and best-studied high-Tc cuprate superconductors, previous measurements had focused on a relatively sparse set of dopings. In this thesis, detailed measurements of the doping dependence of both the microwave penetration depth and surface resistance of YBCO are combined with low-energy muon spin rotation measurements of the absolute magnetic penetration depth to produce a comprehensive doping dependence survey of the microwave conductivity, spanning a wide range of oxygen contents between 6+x = 6.49 and 6.998. The temperature derivatives of the magnetic penetration depth continue to decrease at the highest dopings, challenging previous predictions of a peak in penetration depth near the proposed quantum critical point in the overdoped regime. Additionally, a sudden increase in the a–b anisotropy of low-temperature slopes was observed near optimal doping, suggesting the possibility of additional changes in electronic behaviour in this region. Microwave surface resistance measurements revealed a sharp increase in the scattering rate – along the a axis only – for samples near 1/8th hole doping. Surprisingly, the a-axis scattering rate was discovered to decrease – not increase – after disordering the CuO chain layer oxygen configuration. The short a-axis correlation lengths in this doping range, combined with the strong scattering potential produced by chain order domain boundaries, are proposed as an explanation for this counterintuitive behaviour.
Item Metadata
Title |
A detailed doping survey of the low-energy electrodynamics of YBa2Cu3O6+x
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Creator | |
Publisher |
University of British Columbia
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Date Issued |
2014
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Description |
The rich phenomenology displayed by the high temperature (high-Tc) cuprate superconductors has attracted intense experimental and theoretical attention for nearly thirty years. Despite steady and continued progress, a complete and consistent microscopic theory of the cuprates continues to elude researchers. However, recent work appears to be converging on a picture of separate spin and charge order phase transitions – well below and slightly above optimal doping, respectively – along with associated Fermi surface reconstruction.
As sensitive probes of the low-energy electrodynamics, microwave conductivity techniques are well-suited for characterizing the effects of such changes in electronic structure. For YBa₂Cu₃0₆₊x (YBCO), one of the cleanest and best-studied high-Tc cuprate superconductors, previous measurements had focused on a relatively sparse set of dopings. In this thesis, detailed measurements of the doping dependence of both the microwave penetration
depth and surface resistance of YBCO are combined with low-energy muon spin rotation measurements of the absolute magnetic penetration depth to produce a comprehensive doping dependence survey of the microwave conductivity, spanning a wide range of oxygen contents between 6+x = 6.49 and 6.998.
The temperature derivatives of the magnetic penetration depth continue to decrease at the highest dopings, challenging previous predictions of a peak in penetration depth near the proposed quantum critical point in the overdoped regime. Additionally, a sudden increase in the a–b anisotropy of low-temperature slopes was observed near optimal doping, suggesting the possibility of additional changes in electronic behaviour in this region.
Microwave surface resistance measurements revealed a sharp increase in the scattering rate – along the a axis only – for samples near 1/8th hole doping. Surprisingly, the a-axis scattering rate was discovered to decrease – not increase – after disordering the CuO chain layer oxygen configuration. The short a-axis correlation lengths in this doping range, combined with the strong scattering potential produced by chain order domain boundaries, are proposed as an explanation for this counterintuitive behaviour.
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Genre | |
Type | |
Language |
eng
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Date Available |
2014-08-07
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Provider |
Vancouver : University of British Columbia Library
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Rights |
Attribution-NonCommercial-NoDerivs 2.5 Canada
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DOI |
10.14288/1.0167590
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URI | |
Degree | |
Program | |
Affiliation | |
Degree Grantor |
University of British Columbia
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Graduation Date |
2014-09
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Campus | |
Scholarly Level |
Graduate
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Rights URI | |
Aggregated Source Repository |
DSpace
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Rights
Attribution-NonCommercial-NoDerivs 2.5 Canada