Research Areas

The first HTS wire that carried significant critical current was made from Bi2Sr2CaCu2O8 (Bi-2212) in 1989. We studied it in the ASC in the 1990s and came back to it around 2007.

We address the key underlying scientific and engineering issues of YBa2Cu3O7-x Coated Conductors (CCs). We characterize forefront samples using magneto-optical imaging, SEM, and Jc(H) measurements for the purpose of understanding and resolving key performance issues. Areas of concentration for us include substrates, buffer layers, the superconducting over layer and their complex interactions. CCs are polycrystalline by nature, consisting of multiple GBs and intragrain regions, and we also seek to understand the consequences of this granularity.

Our underlying goal is to understand "real" grain boundaries (GBs) of high Tc superconductors in all their multi-scale complexity. This requires a forefront, mix of sample design and fabrication, film growth, superconducting property characterization, nanoscale microstructure and electronic structure determination, methods to modify GB properties and theory that takes full account of the complex materials science of these materials. Different techniques are being used to address key aspects of current transport through GBs:

LTS stands for "low temperature superconductor," which typically refers to Nb-based alloys (most commonly Nb-47wt.%Ti) and A15 (Nb3Sn and Nb3Al) superconductors that were already in use prior to the discovery of "high temperature" copper-oxide superconductors in 1986. "Temperature" here refers to the temperature below which the superconductor must be cooled in order for it to become superconducting; for LTS superconductors that temperature is usually well below 20 K (-253°C).

In January 2001, a totally new superconductor was discovered, with a surprising critical temperature of 39 K - MgB2. This discovery stimulated a global flurry of work seeking higher Tc and uncovering the basic physics.