1. Data Storage Systems Center, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, USA
2. Department of Materials Science and Engineering, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, USA
3. SYSU-CMU Joint Institute of Engineering, Sun Yat-Sen University, Guangzhou, China
4. SYSU-CMU Shunde International Joint Research Institute, Guangdong, China
5. Department of Electrical and Computer Engineering, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, USA