1. Department of Materials Science and Engineering, and Brockhouse Institute for Materials Research, McMaster University, 1280 Main Street West, Hamilton, Ontario, L8S 4L7, Canada
2. Department of Physics, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
3. Department of Mechanical and Industrial Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA