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Thursday, August 14 • 08:30 - 10:30
Topological Insulators II

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8:30-8:45

Oral: Ryszard Buczko
Topological Crystalline Insulators (Pb,Sn)Te & (Pb,Sn)Se: Surface States & Their Spin Polarization
Co-authors: Shiva Safaei, Perla Kacman

8:45-9:00
Oral: Kai Chang
Topological Phase in Commonly-Used Semiconductors
Co-authors: Dong Zhang, Wen-Kai Lou

9:00-9:30
Invited: Joerg Schaefer 
Elemental Topological Insulator alpha-Sn with Tunable Fermi Level 
Co-authors: Arne Barfuss, Markus Scholz, Lenart Dudy, Andrzej Fleszar, Gang Li, Gustav Bihlmayer, Eli Rotenberg, Hugo Dil, Werner Hanke, Ralph Claesssen

We report on the novel topological insulator alpha-Sn, epitaxially grown on InSb with slight compressive strain. The topological surface state (TSS) results from an unusual band order not based on simple spin-orbit coupling, as shown in advanced slab-layer calculations, and emerges from the second valence band. This is probed directly by angle-resolved photoemission with varied photon energies, to single out bulk versus topological contributions. By spin-resolved photoemission we demonstrate that the TSS is highly spin-polarized with counter-clockwise helicity below the Dirac point [1].


The band situation in alpha-Sn closely resembles that of strained HgTe, which in quantum well films yields topological properties such as the quantum spin Hall effect. This renders alpha-Sn a promising candidate for analogous behavior. It is even predicted that a 2D monolayer of Sn in a hexagonal lattice will exhibit 1D topological edge states [2]. Thus, the elemental material alpha-Sn allows ample modifications of the topological situation. As a key step, we demonstrate precise control of the Fermi level in relation to the Dirac point by addition of dopants [1].

[1] A. Barfuss et al., Phys. Rev. Lett. 111, 157205 (2013).
[2] Y. Xu et al., Phys. Rev. Lett. 111, 136804 (2013).

9:30-9:45
Oral: Atindra Nath Pal
Insulating State & Strong Non-Local Response Near the Charge Neutrality Point in an InAs/GaSb Composite Quantum Well
Co-authors: Fabrizio Nichele, Susanne Mueller, Patrick Pietsch, Thomas Ihn, Klaus Ensslin, Christophe Charpentier, Werner Wegscheider

9:45-10:00
Open

10:00-10:15
Oral: Zhuo Wang
Proximity Effect in the Topological Insulator Bismuth Telluride 
Co-authors: Tianyu Ye, Ramesh Mani 

10:15-10:30
Open 

Session Chairs
GP

Gloria Platero

Instituto de Ciencia de Materiales de Madrid
Gloria Platero did her PhD at the Autonomous University of Madrid. She then spent two years at the Max Planck Institute for High Magnetic Fields in Grenoble (France) as a postdoctoral researcher. Afterwards she got a permanent position at the Solid State Institute of the Spanish research council (CSIC). At present, she is a Research Professor at the Material Science Institute of Madrid (CSIC). | | She is the head of the research group in Madrid... Read More →

Speakers
JS

Joerg Schaefer

University of Wuerzburg


Thursday August 14, 2014 08:30 - 10:30
Room 19A

Attendees (15)