Hope College Physics Department
Research Experiences for Undergraduates
Summer 2009
Project Summary


Project Title: Doping Dependent Microwave Nonlinearity of Tl2Ba2CaCu2O8-x Superconductor
Student Name: Candace Goodson
Student's Home Institution: Hope College
Research Advisor: Dr. Stephen Remillard
Source of Support: This material is based upon work supported by the National Science Foundation under NSF-REU Grant No. PHY-0452206, and a grant from the Research Corp. for Science Advancement.

The carrier doping of the Tl2Ba2CaCu2O8-x (TBCCO-2212) superconductor is a potential tool for modifying the nonlinearity of the superconductor’s microwave response. The properties that respond to carrier doping level include the surface resistance (RS) and critical temperature (TC) of the TBCCO-2212 superconductor. The effect of nitrogen annealing on RS and critical temperature was demonstrated. A sapphire/superconducting dielectric resonator housed in a liquid nitrogen cryostat was tested with a vector network analyzer in order to determine RS and TC. The influence of the induced surface current on RS, called nonlinearity, was found to depend on the doping level, as was the TC. This, in turn, provides a useful correlation of doping level to the temperature of the nitrogen anneal. Nitrogen annealing has thus been shown to provide a calibrated method to select a nonlinearity regime of the superconductor.

Publications and Presentations:
"Doping Dependent Microwave Nonlinearity of Tl2Ba2CaCu2O8", Candace Goodson, West Michigan Undergraduate Research Conference, Grand Rapids, Oct 31, 2009.