PHYSICAL REVIEW LETTERS, vol. 104, no. 3, 2010-01-22
PHYSICAL REVIEW LETTERS, vol. 107, no. 24, 2011-12-07
APPLIED PHYSICS LETTERS, vol. 101, no. 15, page. 152103, 2012-10-08
JOURNAL OF THE KOREAN PHYSICAL SOCIETY, vol. 52, no. 6, page. 1814 - 1817, 2008-06
JOURNAL OF PHYSICS-CONDENSED MATTER, vol. 23, no. 25, page. 256001, 2011-06-29