Strong anisotropic optical conductivity in two-dimensional puckered structures: The role of the Rashba effect

Abstract

We calculate the optical conductivity of an anisotropic two-dimensional system with Rashba spin-flip excitation within the Kubo formalism. We show that the anisotropic Rashba effect caused by an external field changes significantly the magnitude of the spin splitting. Furthermore, we obtain an analytical expression for the longitudinal optical conductivity associated with inter-band transitions as a function of the frequency for an arbitrary polarization angle. We find that the diagonal components of the optical conductivity tensor are direction-dependent and the spectrum of optical absorption is strongly anisotropic with an absorption window. The height and width of this absorption window are very sensitive to the system anisotropy. While the height of absorption peak increases with increasing effective mass anisotropy ratio, the peak intensity is larger when the light polarization is along the armchair direction. Moreover, the absorption peak width becomes broader as the density of state mass or Rashba interaction is enhanced. These features can be used to determine parameters relevant for spintronics through the optical absorption spectrum.

Самоиндуцированная Прозрачность В Монослое Черного Фосфора

“…Следует отметить, что представленный подход (ТМОЗ) является довольно общим и наряду с фосфореном может также применяться для другиx двумерных анизотропных материалов (например, для различных типов двумерных полупроводников: h-BN, MoSe 2 , WSe 2 и т. д. [18,19]), а также в случае, когда проводимость среды σ зависит не только от угла α, но и от волнового числа k и частоты ω несущей волны [1,20]. Более того, здесь мы рассмотрели случай аттенюатора, но этот подход может также применяться для усиливающей среды, экспериментально исследованной в [12][13][14][15][16].…”

High-temperature electron-hole superfluidity with strong anisotropic gaps in double phosphorene monolayers

“…Motivated by this peculiar property, several theoretical and experimental studies investigated different anisotropic properties of phosphorene. [13][14][15] Recently, many-body aspects of phosphorene have been also addressed through the study of collective excitation modes [16][17][18][19][20] in a doped monolayer and Coulomb drag 21 in coupled phosphorene sheets.…”

Plasmon modes in monolayer and double-layer black phosphorus under applied uniaxial strain

“…BP is a semiconductor with puckered orthorhombic structure offering highly anisotropic optical and electronic properties. [1][2][3][4][5] Few-layer BP has a unique feature that its direct bandgap exponentially deceases from 1.5 to 0.35 eV as the number of layers increases from monolayer to its bulk form. This property allows layer-engineering to tune the electronic bandgaps and light absorption spectra of BP.…”