2017/08/31 by Cedric Robert, Cédric Robert, T. Amand +11 · 3 citations
Engineering · Materials Science · Physics and Astronomy · #2D Materials and Applications #Atomic physics #Condensed matter physics #Exciton #Materials science #Monolayer #Nanotechnology #Perovskite Materials and Applications #Physics #Quantum Dots Synthesis And Properties #Quantum mechanics #Spectroscopy #cond-mat.mes-hall #cond-mat.mtrl-sci
paper · pdf · doi:10.1103/physrevb.96.155423
published as Phys. Rev. B 96, 155423 (2017)
openalex publication_date 2017/10/09 · arxiv created 2018/05/09 · arxiv updated 2018/05/11 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/06
The intricate interplay between optically dark and bright excitons governs the light-matter interaction in transition metal dichalcogenide monolayers. We have performed a detailed investigation of the ``spin-forbidden'' dark excitons in WSe2 monolayers by optical spectroscopy in an out-of-plane magnetic field Bz. In agreement with the theoretical predictions deduced from group theory analysis, magnetophotoluminescence experiments reveal a zero-field splitting \ensuremathδ=0.6\ifmmode±\else\textpm\fi0.1\phantom\rule0.16em0exmeV between two dark exciton states. The low-energy state is strictly dipole forbidden (perfectly dark) at Bz=0, while the upper state is partially coupled to light with z polarization (``gray'' exciton). The first determination of the dark neutral exciton lifetime \ensuremathτD in a transition metal dichalcogenide monolayer is obtained by time-resolved photoluminescence. We measure \ensuremathτD\ensuremath∼110\ifmmode±\else\textpm\fi10\phantom\rule0.16em0exps for the gray exciton state, i.e., two orders of magnitude longer than the radiative lifetime of the bright neutral exciton at T=12\phantom\rule0.16em0exK.