1. S. Mathews, Department of Materials and Nuclear Engineering, University of Maryland, College Park, MD 20742, USA.
2. R. Ramesh, Department of Materials and Nuclear Engineering and Center for Superconductivity Research, University of Maryland, College Park, MD 20742, USA.
3. T. Venkatesan, Center for Superconductivity Research, University of Maryland, College Park, MD 20742, USA.
4. J. Benedetto, Army Research Laboratory, Adelphi, MD 20783–1197, USA.