Hope College Physics Department
Research Experiences for Undergraduates
Summer 2010
Project Summary


Project Title: Characterization of High Temperature Superconducting Microstrip Lines
Student Name: Annelle Eben
Student's Home Institution: Calvin 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/DMR-1004811 as well as by a Cottrell College Science award from the Research Corporation for Science Advancement.

When two or more frequencies are sent through a High Temperature Superconducting (HTS) resonator, intermodulation (IMD) and harmonic distortion is generated. Because distortion is dependant on the physical properties of the HTS microstrip lines, the microstrip lines were analyzed optically with a traveling microscope to determine their dimensions. Using these dimensions, electromagnetic field simulations with IE3D from Zeland Software provided information about current distributions and the geometry factors of the microstrip lines. The edges of the microstrip lines were imaged with an electron scanning microscope because their microstructure corresponds to fluxon nucleation, which increases the distortion. Multi-tone measurements can be performed to detect the distortion, of which the three-tone method developed at Hope College allows for simultaneous and synchronous measurement of even and odd order distortion currents. Contrary to earlier predictions of solely odd order distortion arising from HTS materials, both even and odd order non-linearity was observed, indicating Time-Reversal Symmetry Breaking (TRSB) in superconducting current. The second and third order distortion measurements are pertinent to current research in HTS in multiple ways: the distortion defines the limitations of microwave technologies and it reveals the fundamental physics of HTS materials. An observed catastrophic increase in the odd order IMD near the phase transition corresponds to the anticipation of the non-linear Meissner effect in HTS. A smaller observed catastrophe in the even order IMD has no current theoretical explanation, but the significant drop in the ratio of second to third order IMD at the phase transition indicates a decline in TRSB.

Publications and Presentations:
S.K. Remillard and Anelle M. Eben, Calvin College Department of Physics and Astronomy, "Time Reversal Symmetry Breaking in Superconducting Devices." 2010 department seminar.

"Even and Odd Order Nonlinearity from Superconductive Microstrip Lines,"Annelle M. Eben, V. Andrew Bunnell, Candace J. Goodson, Evan K. Pease, Sheng-Chiang Lee, and S.K. Remillard, IEEE Trans. on Applied Superconductivity, Vol. 21, no. 3, pp. 595-598, (2011).