Intravalley scattering probed by excitation energy dependence of valley polarization in monolayer MoS2

Steady-state valley polarization by polarized photoexcitation with various excitation energy reveals the intravalley scattering from B exciton to A exciton in a monolayer MoS2. By increasing the excitation energy of circularly polarized light from nearly A exciton, valley polarization detected at the A-exciton is monotonously decreased and completely suppressed due to phonon-mediated scattering. However, the excitation above B exciton energy recovers the valley polarization in the A exciton. By considering the suppressed valley coherence and sign of valley polarization together with the higher energy shift of the recovered peak polarization from B exciton resonance, the polarization recovery originates from the intravalley scattering mediated by phonon from B exciton to A exciton in the same valley.