Optical Absorption in Periodic Graphene Superlattices: Perpendicular Applied Magnetic Field and Temperature Effects

Abstract

A detailed study of the magneto-optical absorption β( ω) is presented for graphene superlattices (SLs) subjected to a perpendicular magnetic field. For a given temperature, this quantity exhibits a resonant peak structure whose characteristics depend on the magnetic field regime, circular polarization of light and SL barrier height. For the intermediate field regime, we demonstrated that the resonant peak structure of β( ω) is directly correlated to the partial joint density of states. Specifically, the latter exhibits van Hove-like singularities and peaks at energies where β( ω) takes its maximum values. We also investigated the magnetoabsorption in the weak field regime for SLs exhibiting one and extra Dirac points in the absence of the field. It was found that for SLs with only one Dirac point, the absorption spectra consist of resonant peaks satisfying the same circular polarization dependent selection rule as that for pristine graphene, except for one of them. For SLs with extra Dirac points, the resonant peaks arise from transitions between singlet subbands or between doublet subbands and satisfy a circular polarization and peak intensity dependent selection rule. It was also found that the resonant structure of β( ω) can be observed experimentally at room temperature in clean SLs.The ORCID identification number(s) for the author(s) of this article can be found under https://doi.

Magnetoconductivity in quasiperiodic graphene superlattices

“…. is the energy quantum number, k y is the conserved wavevector along the y-axis, and the spinor � nk y (x) satisfies the system of differential equations 22 :…”

“…( 1 ) and ( 2 ), are the eigenvalues and eigenfunctions of the massless Dirac-like equation. We can then write in coordinate representation in the form 22 : where is the energy quantum number, is the conserved wavevector along the y -axis, and the spinor satisfies the system of differential equations 22 : I being the unit matrix, the raising and lowering operators, and the conserved center position.…”

Interminiband absorption in a quantum ring superlattice in magnetic field with periodic vector potential

“…Since the appearance of the works of Azbel [25] and Hofstadter [26], the study of electronic spectra in a twodimensional lattice under the influence of a transverse (perpendicular to the lattice plane) magnetic field has become a field of continuous interest [14,[27][28][29][30][31][32][33][34]. Re- * Electronic address: vram@ysu.am cently the consideration of two-dimensional electrons in a spatially periodic transverse magnetic field or periodic magnetic potential is of special interest [28,32,[35][36][37].…”