title: Valley splitting and polarization by the Zeeman effect in monolayer MoSe2.
abstract: 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.
authors.affiliation: Departments of Physics and Electrical Engineering, Columbia University, New York, New York 10027, USA.
authors.forename: Yilei
authors.initials: Y
authors.lastname: Li
authors.affiliation: National High Magnetic Field Laboratory, Tallahassee, Florida 32312, USA.
authors.forename: Jonathan
authors.initials: J
authors.lastname: Ludwig
authors.affiliation: Departments of Physics and Electrical Engineering, Columbia University, New York, New York 10027, USA.
authors.forename: Tony
authors.initials: T
authors.lastname: Low
authors.affiliation: Departments of Physics and Electrical Engineering, Columbia University, New York, New York 10027, USA.
authors.forename: Alexey
authors.initials: A
authors.lastname: Chernikov
authors.affiliation: Department of Mechanical Engineering, Columbia University, New York, New York 10027, USA.
authors.forename: Xu
authors.initials: X
authors.lastname: Cui
authors.affiliation: Department of Mechanical Engineering, Columbia University, New York, New York 10027, USA.
authors.forename: Ghidewon
authors.initials: G
authors.lastname: Arefe
authors.affiliation: Department of Mechanical Engineering, Columbia University, New York, New York 10027, USA.
authors.forename: Young Duck
authors.initials: YD
authors.lastname: Kim
authors.affiliation: Department of Mechanical Engineering, Columbia University, New York, New York 10027, USA.
authors.forename: Arend M
authors.initials: AM
authors.lastname: van der Zande
authors.affiliation: Departments of Physics and Electrical Engineering, Columbia University, New York, New York 10027, USA.
authors.forename: Albert
authors.initials: A
authors.lastname: Rigosi
authors.affiliation: Departments of Physics and Electrical Engineering, Columbia University, New York, New York 10027, USA.
authors.forename: Heather M
authors.initials: HM
authors.lastname: Hill
authors.affiliation: Departments of Physics and Electrical Engineering, Columbia University, New York, New York 10027, USA.
authors.forename: Suk Hyun
authors.initials: SH
authors.lastname: Kim
authors.affiliation: Department of Mechanical Engineering, Columbia University, New York, New York 10027, USA.
authors.forename: James
authors.initials: J
authors.lastname: Hone
authors.affiliation: National High Magnetic Field Laboratory, Tallahassee, Florida 32312, USA.
authors.forename: Zhiqiang
authors.initials: Z
authors.lastname: Li
authors.affiliation: National High Magnetic Field Laboratory, Tallahassee, Florida 32312, USA.
authors.forename: Dmitry
authors.initials: D
authors.lastname: Smirnov
authors.affiliation: Departments of Physics and Electrical Engineering, Columbia University, New York, New York 10027, USA.
authors.forename: Tony F
authors.initials: TF
authors.lastname: Heinz