Interesting physics of the transition metal dichalcogenide semiconductors : Our recent findings using optics and magneto-optics under high magnetic fields

Semiconducting transition metal dichalcogenides (TMDCs) such as MoS2 have set new paradigms in exploring fundamental physical processes, and potential in valley-electronic device applications. Exciting spin and valley phenomena such as valley-polarization, valley-coherence, valley Zeeman effects and single photon emission have been recently reported in the atomically thin layers of these materials. Overall, it is a rapidly growing area of research which has caught significant attention of the semiconductor community, and the condensed matter physicists at large.

In this talk, I will discuss some of our recent findings, briefly explained as follows. At first, using magnetic fields up to 25 T, we control the valley coherence of excitons in monolayer WS2, as revealed by linear polarization resolved magneto-photoluminescence experiments.[1] This will be followed by the discussion of our recent magneto-reflectance study, which when combined with ab-initio DFT-GW based calculations, provides the first evidence of the presence of interlayer indirect-excitons in TMDCs. As a striking result, we find that the salient features of the monolayer- and bilayer-physics are contained in the bulk TMDCs. Afterwards, I will discuss the experimental and theoretical evidence of the strongly in-plane polarized excitons in thin layers of a new member of the TMDC family - ReSe2. This work is performed in collaboration with TIFR. Finally, if time permits, I will discuss our recent experimental and theoretical work regarding the Lande g-factors of excitons in TMDCs, as a function of layer thickness.

[1] "Magnetic-Field-Induced Rotation of Polarized Light Emission from Monolayer WS2", Schmidt-Arora et al., Phys. Rev. Lett. 117 (7), 077402