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Author: Friedhelm Bechstedt
Requested Type: Oral
Submitted: 2015-03-24 07:58:05

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Contact Info:
Friedrich-Schiller-Universitaet Jena
Max-Wien-Platz 1
Jena,   07745
Germany

Abstract Text:
The graphene-like but Si-, Ge-, and Sn-derived honeycomb crystals have attracted much attention due their unique properties [1] and their realization in experiments [2]. We study their optical properties by means of ab initio electronic-structure calculations. The relation of the optical conductivity of an infinitely thin sheet crystal to the modification of absorbance, transmittance and reflectance is derived. Such optical conductivities are determined within a supercell approach [3]. Independent of the group-IV element and the degree of hybridization a universal IR absorbance ruled by the Sommerfeld finestructure constant is found [4, 5]. We demonstrate that near van Hove singularities in the visible and UV frequency range significant modifications of optical properties even due to an atomically thin layer occur [3, 6].

[1] L. Matthes, F.B., PRB 90, 165431 (2014)
[2] P. Vogt et al., PRL 108, 155501 (2012)
[3] L. Matthes et al., New J. Phys. 16, 105007 (2014)
[4] F. Bechstedt et al., APL 100, 264906 (2012)
[5] L. Matthes et al., PRB 87, 035438 (2013)
[6] L. Matthes et al., J. Phys.: CM 25, 395305 (2013)

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