Here’s a link to and a citation for the paper,
by Hyunjae Lee, Tae Kyu Choi, Young Bum Lee, Hye Rim Cho, Roozbeh Ghaffari, Liu Wang, Hyung Jin Choi, Taek Dong Chung, Nanshu Lu, Taeghwan Hyeon, Seung Hong Choi, & Dae-Hyeong Kim. Nature Nanotechnology (2016) doi:10.1038/nnano.2016.38 Published online 21 March 2016
This paper is behind a paywall.
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