Interlayer optical response of yttrium barium (copper (cobalt, zinc)) oxide

We report optical reflectance and spectroscopic ellipsometry measurements of the in- and out-of-plane dielectric responses of chain substituted $\rm YBa\sb2Cu\sb3O\sb{6 + x}$ and $\rm YBa\sb2(Cu\sb{1 - y}Co\sb{y})\sb3O\sb{6 + x}$ and of plane substituted $\rm YBa\sb2(Cu\sb{1 - y}Zn\sb{y})\sb3O\sb{6 + x}.$ A dramatic decrease in the low-frequency c-axis optical conductivity, σ\sb{\rm c}(ω), is observed with either O reduction or Co substitution, suggesting that structural changes in the Cu(1)-O(4)-Cu(2) complex between the CuO$\sb2$ bilayers dominate the doping dependence of interlayer coupling in $\rm YBa\sb2(Cu\sb{1 - y}M\sb{y})\sb3O\sb{6 + x}$ (M = Co, Zn). The slight decrease in σ\sb{\rm c}(ω) observed with Zn substitution suggests that the charge dynamics in the CuO$\sb2$ planes play at best a minor role in regulating interlayer hopping. We find that the electronic component of the c-axis optical conductivity in $\rm YBa\sb2Cu\sb3O\sb{6 + x}$ is roughly constant below 800 cm$\sp{-1}$, and is well fit over the frequency range 800 cm\rm\sp{-1} \leω\le3200 cm\sp{-1} by σ\sb{\rm c}(ω)\proptoω\spγ (0 \leγ<1.2), for all oxygen concentrations $\rm 0.26 \le x \le 0.93.$ The consequences of these results for theories of c-axis transport in the cuprates are discussed. Absorption bands near 0.95 and 2.7 eV in σ\sb{\rm c}(ω) are assigned to plane-to-chain antibonding band transitions, while the c-axis polarized 1.7 eV absorption is attributed to charge transfer transitions between O and Cu atoms in adjacent CuO$\sb2$ planes of a bilayer. We consider the proposed connection between the pseudogap in the c-axis optical conductivity, and the deviations from linearity in the in- and out-of-plane resistivity, and discuss the possibility that either interlayer dynamic disorder or low-q spin scattering may account for these unusual features. Notably, c-axis polarized electronic Raman scattering measurements are discussed that provide evidence for a specific incoherent contribution to σ\sb{c}(ω) resulting from optical phonon assisted interlayer hopping.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Physics

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2011

Author dc:creator

• Karlow, Marvin Anthony

Contributors dc:contributor

• Wolfe, J.P.

• Physics, Condensed Matter

Statement dc:rights

• Copyright 1996 Karlow, Marvin Anthony

Language dc:language

eng

Identifier

9780591087970
AAI9702554
(UMI)AAI9702554

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/19570