[seminar] DANAS, SEMINAR na IF-u u CETVRTAK, 04. 11. 2010.

[Ivica Zivkovic]

**

**

*Institut za fiziku, Bijenička cesta 46,*

*predavaonica u zgradi Mladen Paić*

*četvrtak, 4. studenog 2010, u 15:00 sati*

*Graphene and Topological Insulators*

**

*Dr. Carsten Busse***

**

*II. Physikalisches Institut, Universität zu Köln,*

*Zülpicher Str.77, 50937 Köln, Germany*

**

*/E-mail: busse at ph2.uni-koeln.de <mailto:busse at ph2.uni-koeln.de>/*

*The scanning tunneling microscope (STM) is a powerful tool to study not 
only the geometric, but also the electronic structure of surfaces in 
atomic resolution. In this talk I will address the application of STM to 
two fascinating systems that have stimulated intense research in the 
last years, namely graphene and topological insulators.*

*The new material graphene (Noble Prize in Physics 2010) currently 
receives an enormous attention for its exciting properties [1], caused 
by its monoatomic thickness and the unique band structure arising from 
its lattice symmetry. Here, we study the epitaxial growth of graphene on 
Ir(111), which leads to graphene of high structural quality which is 
only weakly bonded to the substrate [2-4]. Complementing STM, we 
determined key structural parameters using an x-ray standing wave (XSW) 
analysis. The results are corroborated by extensive DFT-calculations 
incorporating nonlocal interactions. Furthermore, graphene on Ir(111) is 
a template for the growth of metal cluster lattices (Ir, Pt, W, Re, Au, 
Fe) [5,6] showing a narrow size distribution and exceptional thermal 
stability.*

*Topological insulators (TI) represent a new class of materials showing 
a bulk gap like an ordinary insulator but conducting states on their 
surface. These surface states are topologically protected against 
perturbations and impurity scattering by time-reversal invariance (TRI) 
[7]. Here, we study the Te-terminated (111) surface of Bi_2 Te_3 , a 
second generation 3D topological insulator. We investigated the surface 
state by analyzing interference patterns which are generated by 
electrons scattering at defects on the surface.*

**

*[1]A. K. Geim, Science 324, 1530 (2009).*

*[2]J. Coraux et al., Nano Lett/. /8, 565, (2008).*

*[3]R. van Gastel et al., Appl. Phys. Lett. 95, 121901 (2009).*

*[4]I.Pletikosić et al., Phys. Rev. Lett., 102, 056808 (2009).*

*[5] A.T. N'Diaye et al/.,/ Phys. Rev. Lett/., /97, 215501, (2006).*

*[6]A. T. N'Diaye et al., 11, 103045 (2009).*

*[7]M. Hasan C. Kane,arXiv:1002.3895(2010).*

*http://www.ph2.uni-koeln.de/379.html*

*Voditelji seminara IF-a: Berislav Horvatić& Ivica Živković*

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