Scattering of phonons by high-concentration isotopic impurities in ultrathin graphite

Michael Thompson Pettes,1,3 Mir Mohammad Sadeghi,1 Hengxing Ji,1,4 Insun Jo,2 Wei Wu,3 Rodney S. Ruoff,1 and Li Shi1,* 1Department of Mechanical Engineering, Texas Materials Institute, The University of Texas at Austin, Austin, Texas 78712, USA 2Department of Physics, The University of Texas at Austin, Austin, Texas 78712, USA 3Department of Mechanical Engineering, Institute of Materials Science, University of Connecticut, Storrs, Connecticut 06269, USA 4Department of Materials Science and Engineering, CAS Key Laboratory of Materials for Energy Conversion, University of Science and Technology of China, Hefei 230036, China (Received 21 January 2014; revised manuscript received 29 November 2014; published 21 January 2015)