Optical dielectric properties of YBa2Cu3O6+x and Ba1-xKxBiO

Ellipsometry is a technique that measures the change in polarization state of a beam of light on reflection from a surface. The change in polarization state can be calculated from the dielectric function of the surface and knowledge of the interface (roughness, geometry, surface layers, etc.). We have constructed a rotating analyzer ellipsometer (RAE) and modified it to allow measurement of samples significantly smaller than the extent of the incident beam (sample dimensions of about O.lmm are possible). In this work, normal state (room temperature) dielectric properties of two high temperature superconducting systems are studied as a function of doping. For the YBa2Cu3O6+x system, a sharp peak in the imaginary part of the dielectric function near 4.0eV is examined as a function of oxygen doping. The anisotropy present in this system for higher levels of doping is observed to induce a splitting in this peak that is believed to be associated with the local ordering of oxygen in the chains. For the Ba1-xKxBiO3 system, the destruction of the insulating gap and the development of a free carrier response is examined as a function of potassium doping. In this work, data from the ellipsometer is used to complement infrared reflectivity data. The result is the ability to study free carrier response over a wide range of energy.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Physics

Year dc:date

2012

Author dc:creator

• Kotz, Arthur Lewis

Contributors dc:contributor

• Klein, Miles V.

• ellipsometry
• YBa2Cu3O6+x
• Ba1-xKxBiO

Statement dc:rights

• 1992 Arthur Lewis Kotz

Language dc:language

en

Handle dc:identifier

http://hdl.handle.net/2142/28686

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/28686