Single layer transition metal dichalcogenides are 2D semiconducting systems with unique electronic band
structure. Two-valley energy bands along with strong spin-orbital coupling lead to valley-dependent carrier spin
polarization, which is the basis for recently proposed valleytronic applications. These systems also exhibit
unusually strong many body effects, such as strong exciton and trion binding, due to reduced dielectric
screening of Coulomb interactions. Not much is known about the impact of strong many particle correlations on
spin and valley polarization dynamics. Here we report direct measurements of ultrafast valley specific relaxation
dynamics in single layer MoS2 and WS2. We found that excitonic many body interactions significantly
contribute to the relaxation process. Biexciton formation reveals hole valley/spin relaxation time in MoS2. Our
results suggest that initial fast intervalley electron scattering and electron spin relaxation leads to loss of valley
polarization for holes through an electron-hole spin exchange mechanism in both MoS2 and WS2.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.