Observation of intervalley quantum interference in epitaxial monolayer tungsten diselenide.
The extraordinary electronic structures of monolayer transition metal dichalcogenides, such as the spin-valley-coupled band edges, have sparked great interest for potential spintronic and valleytronic applications based on these two-dimensional materials. In this work, we report the experimental observation of quasi-particle interference patterns in monolayer WSe2 using low-temperature scanning tunnelling spectroscopy. We observe intervalley quantum interference involving the Q valleys in the conduction band due to spin-conserving scattering processes, while spin-flipping intervalley scattering is absent. Our results establish unequivocally the presence of spin-valley coupling and affirm the large spin splitting at the Q valleys. Importantly, the inefficient spin-flipping scattering implies long valley and spin lifetime in monolayer WSe2, which is a key figure of merit for valley-spintronic applications.
Physics Department, The University of Hong Kong, Pokfulam Road, Hong Kong.
Hongjun
H
Liu
Physics Department, The University of Hong Kong, Pokfulam Road, Hong Kong.
Jinglei
J
Chen
Physics Department, The University of Hong Kong, Pokfulam Road, Hong Kong.|Center of Theoretical and Computational Physics, The University of Hong Kong, Pokfulam Road, Hong Kong.
Hongyi
H
Yu
Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), Department of Physics and Astronomy, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240, China.
Fang
F
Yang
Physics Department, The University of Hong Kong, Pokfulam Road, Hong Kong.
Lu
L
Jiao
School of Physics, Beijing Institute of Technology, Beijing 100081, China.
Gui-Bin
GB
Liu
Physics Department, The University of Hong Kong, Pokfulam Road, Hong Kong.
Wingking
W
Ho
Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), Department of Physics and Astronomy, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240, China.|Innovation Center of Advanced Microstructures, Nanjing, China.
Chunlei
C
Gao
Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), Department of Physics and Astronomy, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240, China.|Innovation Center of Advanced Microstructures, Nanjing, China.
Jinfeng
J
Jia
Physics Department, The University of Hong Kong, Pokfulam Road, Hong Kong.|Center of Theoretical and Computational Physics, The University of Hong Kong, Pokfulam Road, Hong Kong.
Wang
W
Yao
Physics Department, The University of Hong Kong, Pokfulam Road, Hong Kong.
Maohai
M
Xie