The ab initio calculation of optical spectra of sheet crystals usually arranges them in a three-dimensional superlattice with a sufficiently large interlayer distance. We show how the resulting frequency-dependent dielectric tensor is related to the anisotropic optical conductivity of an individual sheet or to the dielectric tensor of a corresponding film with thickness d. Their out-of-plane component is taken into account, in contrast to usual treatments. We demonstrate that the generalized transfer-matrix method to model the optical properties of a layer system containing a sheet crystal accounts for all tensor components. As long as d≪λ ( -wavelength of light) this generalized formulation of the optical properties for anisotropic two-dimensional (2D) systems of arbitrary thickness reproduces the limits found in literature that are based either on electromagnetic boundary conditions for a conducting surface or on an isotropic dielectric tensor. For s-polarized light, the results are independent of the sheet description. For oblique incidence of p-polarized light, the tensor nature of the optical conductivity (or the dielectric function) of the sheet crystal strongly impacts on reflectance, transmittance, and absorbance due to the out-of-plane optical conductivity. The limit d→0 should be taken in the final expressions. Example spectra are given for the group-IV honeycomb 2D crystals graphene and silicene.

The ab initio calculation of optical spectra of sheet crystals usually arranges them in a three-dimensional superlattice with a sufficiently large interlayer distance. We show how the resulting frequency-dependent dielectric tensor is related to the anisotropic optical conductivity of an individual sheet or to the dielectric tensor of a corresponding film with thickness d. Their out-of-plane component is taken into account, in contrast to usual treatments. We demonstrate that the generalized transfer-matrix method to model the optical properties of a layer system containing a sheet crystal accounts for all tensor components. As long as d << lambda (lambda-wavelength of light) this generalized formulation of the optical properties for anisotropic two-dimensional (2D) systems of arbitrary thickness reproduces the limits found in literature that are based either on electromagnetic boundary conditions for a conducting surface or on an isotropic dielectric tensor. For s-polarized light, the results are independent of the sheet description. For oblique incidence of p-polarized light, the tensor nature of the optical conductivity (or the dielectric function) of the sheet crystal strongly impacts on reflectance, transmittance, and absorbance due to the out-of-plane optical conductivity. The limit d -> 0 should be taken in the final expressions. Example spectra are given for the group-IV honeycomb 2D crystals graphene and silicene.

Matthes, L., Pulci, O., & Bechstedt, F. (2016). Influence of out-of-plane response of optical properties of two-dimensional materials: first principles approach. PHYSICAL REVIEW. B, 94(20), 205408 [10.1103/PhysRevB.94.205408].

Influence of out-of-plane response of optical properties of two-dimensional materials: first principles approach

PULCI, OLIVIA;
2016

Abstract

The ab initio calculation of optical spectra of sheet crystals usually arranges them in a three-dimensional superlattice with a sufficiently large interlayer distance. We show how the resulting frequency-dependent dielectric tensor is related to the anisotropic optical conductivity of an individual sheet or to the dielectric tensor of a corresponding film with thickness d. Their out-of-plane component is taken into account, in contrast to usual treatments. We demonstrate that the generalized transfer-matrix method to model the optical properties of a layer system containing a sheet crystal accounts for all tensor components. As long as d≪λ ( -wavelength of light) this generalized formulation of the optical properties for anisotropic two-dimensional (2D) systems of arbitrary thickness reproduces the limits found in literature that are based either on electromagnetic boundary conditions for a conducting surface or on an isotropic dielectric tensor. For s-polarized light, the results are independent of the sheet description. For oblique incidence of p-polarized light, the tensor nature of the optical conductivity (or the dielectric function) of the sheet crystal strongly impacts on reflectance, transmittance, and absorbance due to the out-of-plane optical conductivity. The limit d→0 should be taken in the final expressions. Example spectra are given for the group-IV honeycomb 2D crystals graphene and silicene.
Pubblicato
Rilevanza internazionale
Articolo
Esperti anonimi
Settore FIS/03 - Fisica della Materia
English
The ab initio calculation of optical spectra of sheet crystals usually arranges them in a three-dimensional superlattice with a sufficiently large interlayer distance. We show how the resulting frequency-dependent dielectric tensor is related to the anisotropic optical conductivity of an individual sheet or to the dielectric tensor of a corresponding film with thickness d. Their out-of-plane component is taken into account, in contrast to usual treatments. We demonstrate that the generalized transfer-matrix method to model the optical properties of a layer system containing a sheet crystal accounts for all tensor components. As long as d << lambda (lambda-wavelength of light) this generalized formulation of the optical properties for anisotropic two-dimensional (2D) systems of arbitrary thickness reproduces the limits found in literature that are based either on electromagnetic boundary conditions for a conducting surface or on an isotropic dielectric tensor. For s-polarized light, the results are independent of the sheet description. For oblique incidence of p-polarized light, the tensor nature of the optical conductivity (or the dielectric function) of the sheet crystal strongly impacts on reflectance, transmittance, and absorbance due to the out-of-plane optical conductivity. The limit d -> 0 should be taken in the final expressions. Example spectra are given for the group-IV honeycomb 2D crystals graphene and silicene.
Matthes, L., Pulci, O., & Bechstedt, F. (2016). Influence of out-of-plane response of optical properties of two-dimensional materials: first principles approach. PHYSICAL REVIEW. B, 94(20), 205408 [10.1103/PhysRevB.94.205408].
Matthes, L; Pulci, O; Bechstedt, F
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2108/173480
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