Dresden 2017 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 79: Electronic Structure of Surfaces: Spectroscopy, Surface States I

O 79.3: Vortrag

Mittwoch, 22. März 2017, 15:45–16:00, WIL C307

Bulk and surface states on the Weyl-semimetal candidate Tellurium (Te) probed by angle-resolved photoemission — •Florian Titze1, Mattia Mulazzi1, Maryam Nazarzadehmoafi1, Christoph Janowitz1, Taichi Okuda2, Kazuki Sumida3, and Andrei Varykhalov41Humboldt Universität zu Berlin — 2Hiroshima Synchrotron Radiation Centre — 3Hiroshima Graduate School of Science — 4Helmholtz Zentrum Berlin

Te is a direct semiconductor with a band gap of 330 meV. At ambient conditions it crystallises in a hexagonal unit cell with 3 inequivalent atoms winding along its c-axis to form left & right helices making it non-centrosymmetric and chiral.

Lacking a symmetry centre together with a strong spin-orbit coupling induces exotic properties: The nested bands near the top of the valence band (at the H point of the Brillouin zone) provide conducting channels for holes, making Te a good thermoelectric material. Furthermore, non-degenerate bands cross near H at a point called a Weyl node, which is a source of Berry curvature. Because of this, the electron spin near H is predicted to be locked parallel to the electron momentum.

With high resolution angle-resolved photoemission spectroscopy, we mapped the electronic structure in great detail, parallel & perpendicular to the surface plane. We compared our data with bulk band structure calculations in order to identify electronic states and surface states. Bands around H were investigated with higher resolution to find the predicted Weyl points.

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