We theoretically study the magneto-optical transport properties of monolayer molybdenum disulfide (${\mathrm{MoS}}_2$) on polar substrates in the presence of a perpendicular magnetic field. The magneto-optical absorption coefficient (MOAC) is investigated as a function of the incident photon energy when carriers are scattered by three different types of phonons: the intrinsic ${\mathrm{MoS}}_2$ acoustic, optical phonons, and the surface optical (SO) phonons induced by polar substrates. Among the substrates considered, the largest magnitude of MOAC and full-width at half maximum (FWHM) are observed for a ${\mathrm{SiO}}_2$ substrate over the entire temperature and magnetic field range considered due to its strongest electron-SO phonon scattering, while an h-BN substrate displays the lowest one. The piezoelectric (PE) coupling to the transverse (TA) phonon is shown to dominate the MOAC and FWHM due to intrinsic acoustic phonon scattering. Meanwhile, these properties for intrinsic optical phonons are dominated by zero-order deformation potential (DP) couplings and the Fröhlich interaction. The dependence of the MOAC and FWHM on temperature, magnetic field, and the effective ${\mathrm{MoS}}_2$-substrate distance is also examined. The present results for monolayer ${\mathrm{MoS}}_2$ are compared with those in conventional two-dimensional systems as well as in graphene. Our results show that SO phonons play a crucial role at high temperature depending on the substrates and have a non-negligible effect on the magneto-optical transport properties of monolayer ${\mathrm{MoS}}_2$, which could be further experimentally and theoretically investigated in the future.

In this paper, we study the structural and electronic properties of graphene adsorbed on MoS₂ monolayer (G/MoS₂) with different stacking configurations using dispersion-corrected density functional theory. Our calculations show that the interaction between graphene and MoS₂ monolayer is a weak van der Waals interaction in all four stacking configurations with the binding energy per carbon atom of −30 meV. In the presence of MoS₂ monolayer, the linear bands on the Dirac cone of graphene at the interfaces are slightly split. A band gap about 3 meV opens in G/MoS₂ interfaces due to the breaking of sublattice symmetry by the intrinsic interface dipole, and it could be effectively modulated by the stacking configurations. Furthermore, we found that an n-type Schottky contact is formed at the G/MoS₂ interface in all four stacking configurations with a small Schottky barrier about 0.49 eV. The appearance of the non-zero band gap in graphene has opened up new possibilities for its application in electronic devices such as graphene field-effect transistors.

We study the optical absorption properties of silicene and germanene in the presence of the perpendicular magnetic and electric fields. Their low-energy Landau level (LL) spectra are controllable by an external electric field, where the spin- and valley-degeneracy of the LLs are strongly influenced by the electric and Zeeman fields. The electric field has removed spin-degeneracy at a given valley. Analytical expressions for the magneto-optical absorption coefficient (MOAC) are expressed in the presence of the interaction between carriers and random impurities and the intrinsic phonons including the spin and valley effects. The results evaluated for the topological insulator and valley-spin-polarized metal phases showed that when the electric field is included, the MOAC peaks are separated for opposite spin cases where the splitting in germanene is stronger than that in silicene. The peak's intensity caused by the carrier-photon-impurity scattering is the highest, the next is the carrier-photon scattering, while the carrier-photon-phonon scattering shows the lowest in both materials. Among the different phonon modes, the out-of-plane (ZA) mode in silicene dominates the others, being attributed to its buckled atomic structure, which does not exist in graphene. When the ZA mode is taken into account, the estimated resultant mobility from the full-width at half-maximum is significantly supported by the experimental result in silicene.