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Phys Rev Lett. 2014 Dec 31;113(26):266804. doi: 10.1103/PhysRevLett.113.266804. Epub 2014 Dec 23.

Valley splitting and polarization by the Zeeman effect in monolayer MoSe2.

Physical review letters

Yilei Li, Jonathan Ludwig, Tony Low, Alexey Chernikov, Xu Cui, Ghidewon Arefe, Young Duck Kim, Arend M van der Zande, Albert Rigosi, Heather M Hill, Suk Hyun Kim, James Hone, Zhiqiang Li, Dmitry Smirnov, Tony F Heinz

Affiliations

  1. Departments of Physics and Electrical Engineering, Columbia University, New York, New York 10027, USA.
  2. National High Magnetic Field Laboratory, Tallahassee, Florida 32312, USA.
  3. Department of Mechanical Engineering, Columbia University, New York, New York 10027, USA.

PMID: 25615372 DOI: 10.1103/PhysRevLett.113.266804

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.

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