Physical Review Letters, 103-15, 2009 doi:10.1103/PhysRevLett.103.156801
Sakamoto Kazuyuki, Kakuta Haruya, Sugawara Katsuaki, Miyamoto Koji, Kimura Akio, Kuzumaki Takuya, Ueno Nobuo, Annese Emilia, Fujii Jun, Kodama Ayaka, Shishidou Tatsuya, Namatame Hirofumi, Taniguchi Masaki, Sato Takafumi, Takahashi Takashi, Oguchi Tamio