bilayer

We studied Zeeman splitting ΔE of different recombination channels in Bilayer MoS₂ using magneto-reflectance spectroscopy. The Zeeman splitting of both A and B excitons of bilayer MoS₂ is linear in magnetic field with a slope of approximately -0.2 meV/T similar to that of single layer MoS₂. In addition, we observed a new feature labeled N at 2.01 eV between A (1.93 eV) and B (2.13 eV) excitons¹. We note that feature N is not observed in MoS₂ monolayers. This new feature shows a positive Zeeman slope of 0.37 meV/T as compared to A and B excitons. Theoretical^2,3 and experimental⁴ studies show that bilayer MoS₂ exhibits optical properties resulting from an interplay of the direct-bandgap of monolayer system, and the indirect bandgap of the bulk. A crucial property of the bilayer system appears to be its inversion symmetry² and tuning³ of that symmetry translates into the interplay of contributions of different valleys in the photoluminescence spectra and possible appearance of additional emission⁴. We hypothesize that feature ‘N’ results from these valley-mixing effects.
1. K.F. Mak et al., Phys. Rev. Lett. 105, 136805 (2010)
2. E. S. Kadantsev and P. Hawrylak, Solid State Commun. 152, 909 (2012).
3. S. Wu et al., Nature Physics 9, 149 (2013)
4. T. Chu et al., Nano Lett. 15, 8000 (2015)