Optical orientation with linearly polarized light in transition metal dichalcogenides

Abstract

We study the optical properties of semiconducting transition metal dichalcogenide monolayers under the influence of strong out-of-plane magnetic fields, using the effective massive Dirac model. We pay attention to the role of spin-orbit coupling effects, doping level and electron-electron interactions, treated at the Hartree-Fock level. We find that optically-induced valley and spin imbalance, commonly attained with circularly polarized light, can also be obtained with linearly polarized light in the doped regime. Additionally, we explore an exchange-driven mechanism to enhance the spinorbit splitting of the conduction band, in n-doped systems, controlling both the carrier density and the intensity of the applied magnetic field. arXiv:1811.04003v2 [cond-mat.mes-hall]

Magneto-optical absorption in silicene and germanene induced by electric and Zeeman fields

“…This rate is bigger for the acoustic phonon in comparison to the optical phonon interaction, being in agreement with what happened in the monolayer transition-metal dichalcogenides [31]. Using these FWHM data and the equation (30), the mobility of germanene can be evaluated in the unit of cm 2 /(V s) as μ ac = 8.846 × 10 3 and μ op = 6.297 × 10 4 at T = 300 K and n e = 3 × 10 12 cm −2 , which leads to a resultant mobility value of μ = 7.756 × 10 3 cm 2 /(V s). In comparison, the mobilities due to the acoustic phonon interaction in germanene have achieved at μ TA = 8.82 × 10 4 cm 2 /(V s) and μ LA = 1.34 × 10 5 cm 2 /(V s) [42], which leads to a resultant mobility of μ ac = 5.319 × 10 4 cm 2 /(V s).…”

“…The magneto-optical absorption is one of the important properties studied in the literature in bulk semiconductors [24], low-dimensional systems [25][26][27], and more recently in monolayers of graphene [28] and transition-metal dichalcogenides (TMDCs) [29][30][31]. In this phenomenon, in quantizing magnetic field, optical absorption takes place by absorbing a photon and making inter-Landau level transition with/without the assistance of impurity or phonons scattering.…”

Magneto-optical effects in the Landau level manifold of 2D lattices with spin-orbit interaction

“…For finite µ F and n, the allowed transitions are ∆ (n−1)n , ∆ −(n−1)n and ∆ −(n+1)n , however the latter two are large energies with diminished contributions to the magneto-optical conductivities, Eqs. (8) and (9). Hence, the allowed transition is the one that immediately across the chemical potential and results in a single large peak in all magneto-optic signatures.…”

Foldy-Wouthuysen transformation for gapped Dirac fermions in two-dimensional semiconducting materials and valley excitons under external fields

“…A valley exciton is a Wannier-like exciton whose properties are decided by the additional valley degree of freedom and affected by the band-structure geometry [8][9][10][11][12][13]. Various physical phenomena related to valley excitons, such as Berry-curvature induced exciton energy-level splitting [14][15][16][17][18], valley-selected optical transition [9,10,19,20], exciton valley Hall effect [21,22], and exciton valley Zeeman effect [23][24][25][26][27] have been observed experimentally and discussed theoretically. While there are a lot of theoretical works using different methods to study different issues of valley excitons, the connection among different theories and interpretations is not manifest.…”