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Optical Absorption in Periodic Graphene Superlattices: Perpendicular Applied Magnetic Field and Temperature Effects
Author(s) -
de DiosLeyva Melquiades,
HernándezBertrán Michael A.,
Morales Alvaro L.,
Duque Carlos A.,
Phuc Huynh Vinh
Publication year - 2018
Publication title -
annalen der physik
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.009
H-Index - 68
eISSN - 1521-3889
pISSN - 0003-3804
DOI - 10.1002/andp.201700414
Subject(s) - graphene , superlattice , condensed matter physics , magnetic field , physics , polarization (electrochemistry) , circular polarization , perpendicular , absorption (acoustics) , field (mathematics) , dirac (video compression format) , materials science , optics , quantum mechanics , chemistry , geometry , mathematics , pure mathematics , neutrino
A detailed study of the magneto‐optical absorption β ( ℏ 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 ( ℏ 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 ( ℏ 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 ( ℏ ω ) can be observed experimentally at room temperature in clean SLs.