[9p-E206-1~11] CS.5 Code-sharing session of 4.5&17

3:15 PM - 3:30 PM JST(6:15 AM - 6:30 AM UTC)English Presentation

[9p-E206-5] Electric-Field Control of Valley States in Two-Dimensional Moiré Materials

〇Yuto Urano^1,2, Lata Chouhan¹, Kenji Watanabe³, Takashi Taniguchi¹, Ryo Kitaura^1,2 (1.MANA NIMS, 2.Hokkaido Univ., 3.NIMS)

Keywords:

2D-semiconductor,Valleytronics,Quantum manipulation technology

Two-dimensional transition-metal dichalcogenide moiré superlattices offer a promising platform for controlling valley states, but the mechanisms governing valley polarization and coherence remain unclear. We investigate a near-0° WS2/WSe2 moiré heterostructure using time-resolved, polarization-resolved photoluminescence while independently tuning the top- and bottom-gate voltages. A two-dimensional gate map identifies regions where the valley relaxation time is strongly enhanced, reaching the microsecond regime. Valley coherence is then examined under the same conditions using a sensitive photoelastic-modulator-based measurement. Its estimated lifetime shows a different gate dependence from the valley relaxation time, indicating that population relaxation and decoherence are governed by distinct microscopic processes. These results demonstrate electric-field control of long-lived valley polarization and reveal additional limitations on stabilizing coherent valley superposition states.