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MacNeill D, Heikes C, Mak KF, Anderson Z, Kormányos A, Zólyomi V, Park J, Ralph DC. Breaking of valley degeneracy by magnetic field in monolayer MoSe2. PHYSICAL REVIEW LETTERS 2015; 114:037401. [PMID: 25659021 DOI: 10.1103/physrevlett.114.037401] [Citation(s) in RCA: 202] [Impact Index Per Article: 22.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/01/2014] [Indexed: 05/24/2023]
Abstract
Using polarization-resolved photoluminescence spectroscopy, we investigate the breaking of valley degeneracy by an out-of-plane magnetic field in back-gated monolayer MoSe2 devices. We observe a linear splitting of -0.22 meV/T between luminescence peak energies in σ+ and σ- emission for both neutral and charged excitons. The optical selection rules of monolayer MoSe2 couple the photon handedness to the exciton valley degree of freedom; so this splitting demonstrates valley degeneracy breaking. In addition, we find that the luminescence handedness can be controlled with a magnetic field to a degree that depends on the back-gate voltage. An applied magnetic field, therefore, provides effective strategies for control over the valley degree of freedom.
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Affiliation(s)
- David MacNeill
- Department of Physics, Cornell University, Ithaca, New York 14853, USA
| | - Colin Heikes
- Department of Physics, Cornell University, Ithaca, New York 14853, USA
| | - Kin Fai Mak
- Department of Physics, Cornell University, Ithaca, New York 14853, USA and Kavli Institute at Cornell, Cornell University, Ithaca, New York 14853, USA
| | - Zachary Anderson
- Department of Physics, Cornell University, Ithaca, New York 14853, USA
| | - Andor Kormányos
- Department of Physics, University of Konstanz, D-78464 Konstanz, Germany
| | - Viktor Zólyomi
- Department of Physics, Lancaster University, Lancaster LA1 4YB, United Kingdom
| | - Jiwoong Park
- Kavli Institute at Cornell, Cornell University, Ithaca, New York 14853, USA and Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, USA
| | - Daniel C Ralph
- Department of Physics, Cornell University, Ithaca, New York 14853, USA and Kavli Institute at Cornell, Cornell University, Ithaca, New York 14853, USA
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