Browsing by Author "Trallero-Giner, C."

Now showing 1 - 2 of 2
  • Thumbnail Image
    Item
    Raman scattering owing to magneto-polaron states in monolayer transition metal dichalcogenides
    ([London] : Springer Nature, 2024) Trallero-Giner, C.; Santiago-Pérez, D. G.; Tkachenko, D. V.; Marques, G. E.; Fomin, V. M.
    Magneto-optical measurements are fundamental research tools that allow for studying the hitherto unexplored optical transitions and the related applications of topological two-dimensional (2D) transition metal dichalcogenides (TMDs). A theoretical model is developed for the first-order magneto-resonant Raman scattering in a monolayer of TMD. A significant number of avoided crossing points involving optical phonons in the magneto-polaron (MP) spectrum, a superposition of the electron and hole states in the excitation branches, and their manifestations in optical transitions at various light scattering configurations are unique features for these 2D structures. The Raman intensity reveals three resonant splittings of double avoided-crossing levels. The three excitation branches are present in the MP spectrum provoked by the coupling of the Landau levels in the conduction and valence bands via an out-of-plane A1-optical phonon mode. The energy gaps at the anticrossing points in the MP scattering spectrum are revealed as a function of the electron and hole optical deformation potential constants. The resonant MP Raman scattering efficiency profile allows for quantifying the relative contribution of the conduction and valence bands in the formation of MPs. The results obtained are a guideline for controlling MP effects on the magneto-optical properties of TMD semiconductors, which open pathways to novel optoelectronic devices based on 2D TMDs.
  • Thumbnail Image
    Item
    Transition metal dichalcogenides: magneto-polarons and resonant Raman scattering
    (Lausanne : Frontiers Media, 2024) Trallero-Giner, C.; Santiago-Pérez, D. G.; Tkachenko, D. V.; Marques, G. E.; Fomin, V. M.
    Topological two-dimensional transition metal dichalcogenides (TMDs) have a wide range of promising applications and are the subject of intense basic scientific research. Due to the existence of a direct optical bandgap, nano-optics and nano-optoelectronics employing monolayer TMDs are at the center of the development of next-generation devices. Magneto-resonant Raman scattering (MRRS) is a non-destructive fundamental technique that enables the study of magneto-electronic levels for TMD semiconductor device applications and hitherto unexplored optical transitions. Raman intensity in a Faraday backscattering configuration as a function of the magnetic field B, laser energy, and the circular polarization of light reveals a set of incoming and outgoing resonances with particular spin orientations and magneto-optical interband transitions at the (Formula presented.) - and (Formula presented.) -valleys of the Brillouin zone. This fact unequivocally allows for a straightforward determination of the important band parameters of TMD materials. A generalization of the MRRS theory is performed for the description of the magneto-polaron (MP) effects in the first-order light scattering process. It shows how strongly the simultaneous presence of the conduction and valence bands modifies the MP energy spectrum. The resonant MP Raman intensity reveals three resonant splitting processes of double avoided-crossing levels reflecting the electron-hole pair energy spectrum. The scattering profile allows for quantifying the relative contribution of the conduction and valence bands in the formation of MPs. Many avoided-crossing points due to the electron–phonon interaction in the MP spectrum, a superposition of the electron and hole states in the excitation branches, and their impact on Raman scattering are exceptional features of monolayer TMDs. Based on this, the reported theoretical studies open a pathway toward MRRS and resonant MP Raman scattering characterization of two-dimensional materials.