TitleImaging Spin Dynamics in Monolayer WS2 by Time-Resolved Kerr Rotation Microscopy
Publication TypeJournal Article
Year of Publication2018
AuthorsMcCormick E.J, Newburger M.J, Luo Y.K, McCreary K.M, Singh S., Martin I.B, Cichewicz E.J, Jonker B.T, Kawakami R.K
Journal2d Materials
Date Published01/2018
Abstract

Monolayer transition metal dichalcogenides (TMD) have immense potential for future spintronic and valleytronic applications due to their 2D nature and long spin/valley lifetimes. We investigate the origin of these long-lived states in n-type WS2 using time-resolved Kerr rotation microscopy and photoluminescence microscopy with ~ 1 mu m spatial resolution. Comparing the spatial dependence of the Kerr rotation signal and the photoluminescence reveals a correlation with neutral exciton emission, which is likely due to the transfer of angular momentum to resident conduction electrons with long spin/valley lifetimes. In addition, we observe an unexpected anticorrelation between the Kerr rotation and trion emission, which provides evidence for the presence of long-lived spin/valley-polarized dark trions. We also find that the spin/valley polarization in WS2 is robust to magnetic fields up to 700 mT, indicative of spins and valleys that are stabilized with strong spin-orbit fields.