1. Department
of Materials Science and Engineering and Department of Physics, The University of Texas at Dallas, Richardson, Texas 75080, United States
2. Department
of Physics, UNESP−Sao Paulo State University, Bauru, SP 17033-360, Brazil
3. Instituto
de Física “Gleb Wataghin”, Universidade Estadual de Campinas, UNICAMP, Campinas, SP 13083-859, Brazil