|Title||Imaging Spin Dynamics in Monolayer WS2 by Time-Resolved Kerr Rotation Microscopy|
|Publication Type||Journal Article|
|Year of Publication||2018|
|Authors||McCormick 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|
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.