Experimental and theoretical evidence for the ferromagnetic edge in WSe2nanosheets.
Bulk TMDCs are diamagnetic materials; however, two-dimensional TMDCs exhibit spin polarized edge states, which results in a coupling between the unsaturated transition metal and chalcogenide atoms at the edges. The magnetism in two-dimensional TMDCs broadens their applications in spintronic and multi-functional devices. Herein, by combining macro/micro-magnetic experimental measurements and density functional theory (DFT) calculations, we demonstrate that among five possible edge-terminated WSe2nanosheets only two types have a magnetic ground state, corresponding to the 100% Se edge terminated and 50% Se edge terminated nanosheets, respectively. The calculation results on WSe2clusters and WSe2zig-zag nanoribbons with different terminations and Se coverage rate confirmed that the unpaired electrons of the edge atoms play a crucial role in the appearance of ferromagnetism in WSe2nanosheets. Furthermore, due to the possible quantum confinement effect and surface effect, there exist thickness-dependent magnetic properties, and the magnitude of magnetism at the edge increases as the number of layers decreases.
Department of Physics, Harbin Institute of Technology, Harbin, People's Republic of China. suiyu@hit.edu.cn.
Lei
L
Tao
Fanchen
F
Meng
Shudong
S
Zhao
Yongli
Y
Song
Jianxin
J
Yu
Xianjie
X
Wang
Zhiguo
Z
Liu
Yi
Y
Wang
Bingsheng
B
Li
Yang
Y
Wang
Yu
Y
Sui