Transition metal dichalcogenide monolayers are highly interesting for potential valleytronic applications due to the coupling of spin and valley degrees of freedom and valley-selective excitonic transitions. However, ultrafast recombination of excitons in these materials poses a natural limit for applications, so that a transfer of polarization to resident carriers is highly advantageous. Here, we study the low-temperature spin-valley dynamics in nominally undoped and n-doped MoSe2 monolayers using time-resolved Kerr rotation. In the n-doped MoSe2, we find a long-lived component of the Kerr signal which we attribute to the spin polarization of resident carriers. This component is absent in the nominally undoped MoSe2. The long-lived spin polarization is stable under applied in-plane magnetic fields. Spatially resolved measurements allow us to determine an upper boundary for the electron spin diffusion constant in MoSe2.
@article{arxiv.1706.01802,
title = {Long-lived spin polarization in n-doped MoSe$_2$ monolayers},
author = {Markus Schwemmer and Philipp Nagler and Andreas Hanninger and Christian Schüller and Tobias Korn},
journal= {arXiv preprint arXiv:1706.01802},
year = {2017}
}