Coherent Lattice Vibrations in Mono- and Few-Layer WSe2.
We report the observation of coherent lattice vibrations in mono- and few-layer WSe2 in the time domain, which were obtained by performing time-resolved transmission measurements. Upon the excitation of ultrashort pulses with the energy resonant to that of A excitons, coherent oscillations of the A1g optical phonon and longitudinal acoustic phonon at the M point of the Brillouin zone (LA(M)) were impulsively generated in monolayer WSe2. In multilayer WSe2 flakes, the interlayer breathing mode (B1) is found to be sensitive to the number of layers, demonstrating its usefulness in characterizing layered transition metal dichalcogenide materials. On the basis of temperature-dependent measurements, we find that the A1g optical phonon mode decays into two acoustic phonons through the anharmonic decay process.
Department of Physics, Chungnam National University , Daejeon 305-764, Republic of Korea.|Korea Research Institute of Standards and Science , Daejeon 305-340, Republic of Korea.
Tae Young
TY
Jeong
Department of Physics, Chungnam National University , Daejeon 305-764, Republic of Korea.
Byung Moon
BM
Jin
Department of Physics and Energy Harvest Storage Research Center, University of Ulsan , Ulsan 680-749, Republic of Korea.
Sonny H
SH
Rhim
Graduate School of Energy, Environment, Water, and Sustainability, Korea Advanced Institute of Science and Technology , Daejeon 305-701, Republic of Korea.
Lamjed
L
Debbichi
Korea Research Institute of Standards and Science , Daejeon 305-340, Republic of Korea.
Jaesung
J
Park
Department of Physics, Chungnam National University , Daejeon 305-764, Republic of Korea.
Yu Dong
YD
Jang
Department of Physics, Chungnam National University , Daejeon 305-764, Republic of Korea.
Hyang Rok
HR
Lee
Korea Research Institute of Standards and Science , Daejeon 305-340, Republic of Korea.
Dong-Hun
DH
Chae
Department of Physics, Chungnam National University , Daejeon 305-764, Republic of Korea.
Donghan
D
Lee
Graduate School of Energy, Environment, Water, and Sustainability, Korea Advanced Institute of Science and Technology , Daejeon 305-701, Republic of Korea.
Yong-Hoon
YH
Kim
Korea Research Institute of Standards and Science , Daejeon 305-340, Republic of Korea.
Suyong
S
Jung
Department of Physics, Chungnam National University , Daejeon 305-764, Republic of Korea.
Ki Ju
KJ
Yee
WSe2; anharmonic decay; coherent lattice vibration; monolayer; transition metal dichalcogenides