What Has Been Achieved
A family of longstanding mis-assignments of Raman signatures in 2D transition metal dichalcogenides has been corrected by the collaboration between double resonance Raman spectroscopy experiments and first-principles calculations. Selection rules for intervalley scattering processes in MoS2 have been derived from group theory and verified from first-principles.
Importance of Achievement
The study establishes the dominance of LA(K) phonons in intervalley scattering, a process responsible for the destruction of valley polarization, thus highlighting the need for controlling this phonon mode for future efforts on valleytronic devices.
Unique Features of the MIP That Enabled Project
Close collaboration between synthesis, characterization, and theory efforts.
B. R. Carvalho, Y. Wang, S. Mignuzzi, D. Roy, M. Terrones, C. Fantini, V. H. Crespi, L. M. Malard, and M. A. Pimenta, “Intervalley scattering by acoustic phonons in two-dimensional MoS2 revealed by double-resonance Raman spectroscopy”, Nat. Commun. 8, 14670 (2017).