1. School of Materials Engineering, Purdue
University, West Lafayette, Indiana 47907, USA
2. Birck Nanotechnology Center, Purdue University,
West Lafayette, Indiana 47907, USA
3. Thin Film Physics Division, Department of Physics, Chemistry, and Biology
(IFM), Linköping University, SE-581 83 Linköping,
Sweden
4. School of Electrical and Computer Engineering, Purdue
University, West Lafayette, Indiana 47907, USA