Doping Dependence of Spin-Polarization Dynamics in Monolayer Semiconductors

Transition Metal Dichalcogenides are of particular interest for the study of correlated phases due to their strong Coulomb interactions, relatively large effective masses, and convenient doping accessible to them. In WSe₂, optical spin-pumping combined with dichroism probe allows us to study the spin-polarization dynamics at displacements of several micrometers with a pump-probe measurement. We observe a dramatic change in the mobility of the spin-polarization as a function of electronic doping on the sample. As the doping increases, a sudden change of the nonlocal spin dynamics is observed, indicating orders of magnitude changing in carrier mobility. The non-local measurement also shows significant spin amplification due to electron-electron interactions. Our effort on manipulation of the spin-polarization dynamics forward efforts to utilize two dimensional materials in nanophotonic and spintronic applications.