1. Department of Materials Science and Engineering, Cornell University, Ithaca, New York 14853, USA
2. Department of Materials Science and Engineering and Materials Research Laboratory University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
3. Department of Materials Science and Engineering, University of Florida, Gainesville, Florida, 32611, USA
4. Institute of Engineering Thermophysics, Chinese Academy of Sciences, Beijing 100190, China
5. University of Chinese Academy of Sciences, Beijing 100049, China
6. Inorganic Material Lab, Samsung Advanced Institute of Technology (SAIT), Samsung Electronics, 130 Samsung-ro, Yeongtong-gu, Suwon-si, Gyeonggi-do 16678, South Korea
7. Department of Physics, Missouri University of Science and Technology, Rolla, Missouri 65409, USA
8. Kavli Institute at Cornell for Nanoscale Science, Ithaca, New York 14853, USA
9. Leibniz-Institut für Kristallzüchtung, 12489 Berlin, Germany