1. Department of Physics and Astronomy, University of California , Irvine, CA, USA
2. Department of Materials Science and Engineering, University of California , Irvine, CA, USA
3. Irvine Materials Research Institute, University of California Irvine , Irvine, CA, USA
4. Department of Mechanical Engineering, University of California , Santa Barbara, CA, USA
5. Department of Physics and Texas Center for Superconductivity, University of Houston , Houston, TX , USA