Charge density waves and degenerate modes in exfoliated monolayer 2H-TaS2
Duan Zhang,
Yecun Wu,
Yu-Hsin Su,
Ming-Chien Hsu,
Cormac Ó Coileáin,
Jiung Cho,
Miri Choi,
Byong Sun Chun,
Yao Guo,
Ching-Ray Chang,
Han-Chun Wu
Affiliations
Duan Zhang
Elementary Educational College, Beijing Key Laboratory for Nano-Photonics and Nano-Structure, Capital Normal University, Beijing 100048, People's Republic of China
Yecun Wu
School of Physics, Beijing Institute of Technology, Beijing 100081, People's Republic of China
Yu-Hsin Su
Department of Physics, National Taiwan University, Taipei 106, Taiwan
Ming-Chien Hsu
Department of Physics, National Sun Yat-sen University, Kaohsiung 80424, Taiwan
Cormac Ó Coileáin
School of Physics, Beijing Institute of Technology, Beijing 100081, People's Republic of China
Jiung Cho
Western Seoul Center, Korean Basic Science Institute, Seoul 03579, Republic of Korea
Miri Choi
Chuncheon Center, Korean Basic Science Institute, Chuncheon 24341, Republic of Korea
Byong Sun Chun
Division of Industrial Metrology, Korea Research Institute of Standards and Science, Daejeon 3050340, Republic of Korea
Yao Guo
School of Physics, Beijing Institute of Technology, Beijing 100081, People's Republic of China
Ching-Ray Chang
Department of Physics, National Taiwan University, Taipei 106, Taiwan
Han-Chun Wu
School of Physics, Beijing Institute of Technology, Beijing 100081, People's Republic of China
Charge density waves spontaneously breaking lattice symmetry through periodic lattice distortion, and electron–electron and electron–phonon interactions, can lead to a new type of electronic band structure. Bulk 2H-TaS2 is an archetypal transition metal dichalcogenide supporting charge density waves with a phase transition at 75 K. Here, it is shown that charge density waves can exist in exfoliated monolayer 2H-TaS2 and the transition temperature can reach 140 K, which is much higher than that in the bulk. The degenerate breathing and wiggle modes of 2H-TaS2 originating from the periodic lattice distortion are probed by optical methods. The results open an avenue to investigating charge density wave phases in two-dimensional transition metal dichalcogenides and will be helpful for understanding and designing devices based on charge density waves.
