Chendong Zhang1,2* #, Cong Wang3 #, Feng Yang3, Jing-Kai Huang4, Lain-Jong Li4, Wang Yao5, Wei Ji*3, Chih-Kang Shih*2
1 School of Physics and Technology, Wuhan University, Wuhan 430072, China 2 Department of Physics, University of Texas at Austin, Austin, TX 78712, USA 3 Department of Physics and Beijing Key Laboratory of Optoelectronic Functional Materials and Micro-Nano Devices, Renmin University of China, Beijing 100872, China 4 Physical Sciences and Engineering Division, King Abdullah University of Science and Technology, Thuwal, 23955-6900, Kingdom of Saudi Arabia 5 Department of Physics and Center of Theoretical and Computational Physics, University of Hong Kong, Hong Kong, China
#These authors contributed equally.
DOI:10.1021/acsnano.8b07595 Publication Date: January 28, 2019
Defect engineering is a key approach for tailoring the properties of the emerging two-dimensional semiconductors. Here, we report an atomic engineering of the W vacancy in monolayer WSe2 by single potassium atom decoration. The K decoration alters the energy states and reshapes the wave-function such that previously hidden mid-gap states become visible with well-resolved multiplets in scanning tunneling spectroscopy. Their energy levels are in good agreement with first principle calculations. More interestingly, the calculations show that an unpaired electron donated by the K atom can lead to a local magnetic moment, exhibiting an on off switching by the odd-even number of electron filling. Experimentally the Fermi level is pinned above all defect states due to the graphite substrate, corresponding to an off state. The close agreement between theory and experiment in the off state, on the other hand, suggest a possibility of gate-programmable magnetic moments at the defects.