We have measured circularly polarized photoluminescence in monolayer MoSe2 under perpendicular magnetic fields up to 10 T. At low doping densities, the neutral and charged excitons shift linearly with field strength at a rate of ∓ 0.12 meV/T for emission arising, respectively, from the K and K' valleys. The opposite sign for emission from different valleys demonstrates lifting of the valley degeneracy. The magnitude of the Zeeman shift agrees with predicted magnetic moments for carriers in the conduction and valence bands. The relative intensity of neutral and charged exciton emission is modified by the magnetic field, reflecting the creation of field-induced valley polarization. At high doping levels, the Zeeman shift of the charged exciton increases to ∓ 0.18 meV/T. This enhancement is attributed to many-body effects on the binding energy of the charged excitons.
@article{arxiv.1409.8538,
title = {Valley Splitting and Polarization by the Zeeman Effect in Monolayer MoSe2},
author = {Yilei Li and Jonathan Ludwig and Tony Low and Alexey Chernikov and Xu Cui and Ghidewon Arefe and Young Duck Kim and Arend M. van der Zande and Albert Rigosi and Heather M. Hill and Suk Hyun Kim and James Hone and Zhiqiang Li and Dmitry Smirnov and Tony F. Heinz},
journal= {arXiv preprint arXiv:1409.8538},
year = {2015}
}