Breaking of valley degeneracy by magnetic field in monolayer MoSe2

2014/07/31 by David MacNeill, Colin Heikes, Kin Fai Mak +5 · 1 citation
Physics and Astronomy · #cond-mat.mes-hall

paper · pdf · doi:10.1103/physrevlett.114.037401

published as Phys. Rev. Lett. 114, 037401 (2015) · expanded discussion section, corrected typo in eq. 1

arxiv created 2014/10/09 · arxiv updated 2015/02/03

Abstract

Using polarization-resolved photoluminescence spectroscopy, we investigate valley degeneracy breaking by 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 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 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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• Magnetic-field control of Fermi polaron fine structure and polarization in strained monolayer semiconductors

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