| AVS 66th International Symposium & Exhibition | |
| 2D Materials | Tuesday Sessions |
| Session 2D+EM+MI+NS-TuA |
| Session: | Properties of 2D Materials including Electronic, Magnetic, Mechanical, Optical, and Thermal Properties II |
| Presenter: | Michael Newburger, The Ohio State University |
| Authors: | M. Newburger, The Ohio State University Y.K. Luo, The Ohio State University K.M. McCreary, U.S. Naval Research Laboratory I. Martin, The Ohio State University E. McCormick, The Ohio State University B.T. Jonker, U.S. Naval Research Laboratory R. Kawakami, The Ohio State University |
| Correspondent: | Click to Email |
Monolayer transition metal dichalcogenides (TMDs) have attracted attention due to their long spin/valley lifetimes and ability to couple the helicity of light to spin/valley polarization. Additionally, a strength of TMDs lies in their ability to complement other materials, such as graphene, by acting as a means of optical spin injection or proximity coupling. Recently, multiple groups have demonstrated proximity mediated charge transfer and optical spin injection in TMD/graphene heterostructures. However, the spin transfer dynamics across a TMD/graphene interface remain largely unexplored.
Here we utilize time-resolved Kerr rotation (TRKR) microscopy to image the spatial dependence of spin/valley dynamics in monolayer WSe2/graphene heterostructure devices. Spatial maps demonstrate long-lived spin/valley lifetimes on the bare WSe2 but reveal a quenching of spin-valley signal at the WSe2/graphene interfaces. Time delay scans show these interface lifetimes to be quenched up to 3 orders of magnitude in comparison to bare WSe2. Furthermore, photoluminescence mapping exhibits quenching at the interfaces while photoconductivity is enhanced in these regions, demonstrating efficient charge transfer from WSe2 to graphene. Consequently, we attribute the ultrafast spin/valley quenching to the transfer of spin information by conducted charge carriers.