In transition metal dichalcogenide semiconductor monolayers the spin dynamics of electrons is controlled by the original spin-valley locking effect resulting from the interplay between spin-orbit interaction and inversion asymmetry. As a consequence, for electrons occupying bottom conduction bands, a carrier spin flip occurs only if there is a simultaneous change of valley. However, very little is known about the intra-valley spin relaxation processes. In this work we have performed stationary and time-resolved photoluminescence measurements in high quality WSe2 monolayers. Our experiments highlight an efficient relaxation from bright to dark excitons, due to a fast intra-valley electron transfer from the top to the bottom conduction band with opposite spins. A combination of experiments and theoretical analysis allows us to infer a spin relaxation time of about τs∼10ps, driven by the interplay between Γ-valley chiral phonons and spin-orbit mixing.
@article{arxiv.2407.07188,
title = {Efficient Electron Spin Relaxation by Chiral Phonons in WSe$_2$ Monolayers},
author = {D. Lagarde and M. Glazov and V. Jindal and K. Mourzidis and Iann Gerber and A. Balocchi and L. Lombez and P. Renucci and T. Taniguchi and K. Watanabe and C. Robert and X. Marie},
journal= {arXiv preprint arXiv:2407.07188},
year = {2024}
}