Valley Zeeman Splitting and Valley Polarization of Neutral and Charged Excitons in Monolayer MoTe₂ at High Magnetic Fields

Abstract

Semiconducting transition metal dichalcogenides (TMDCs) give rise to interesting new phenomena in external magnetic fields, such as valley Zeeman splitting and magnetic-field-induced valley polarization. These effects have been reported for monolayers (MLs) of the transition metal diselenides MoSe2 and WSe2 and, more recently, for disulfides MoS2 and WS2. Here, we present helicity-resolved magneto-photoluminescence and magneto-reflectance contrast measurements for MLs of the telluride member of the semiconducting TMDCs, 2H-MoTe2, in magnetic fields up to 29 T in Faraday geometry. Well-resolved valley Zeeman splittings for the neutral A and B excitons (XA0 and XB0) and the charged exciton X± are observed with effective g-factors of −4.6 ± 0.2, – 3.8 ± 0.6, and −4.5 ± 0.3, respectively. The magnetic field induced valley polarization of XA0 and X± reaches 78% and 36%, respectively, at a magnetic field of 29 T.