1. Department of Materials Science and Engineering Massachusetts Institute of Technology Cambridge MA 02139 USA
2. Department of Materials and Metallurgical Engineering Bangladesh University of Engineering and Technology Dhaka 1000 Bangladesh
3. Associate, Physical Measurement Laboratory National Institute of Standards and Technology Boulder CO 80305 USA
4. Department of Physics University of Colorado Boulder Boulder CO 80309 USA
5. National Institute of Standards and Technology Boulder CO 80305 USA
6. Department of Electrical Engineering and Computer Science Massachusetts Institute of Technology Cambridge MA 02139 USA
7. Center for Memory and Recording Research University of California‐San Diego La Jolla CA 92093 USA