Regensburg 2019 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 12: HL Poster I

HL 12.27: Poster

Montag, 1. April 2019, 17:30–20:00, Poster E

Plasmonic modes in micro-ribbon arrays of topological insulators — •Philipp Warzanowski, Muhamad Saleh, Andrea Bliesener, Gertjan Lippertz, Yoichi Ando, and Markus Grüninger — Institute of Physics II, University of Cologne, Germany

The electronic surface states of topological insulators offer a rich playground to study unconventional plasmonic excitations in 2D by optical spectroscopy [1,2]. Spin-momentum locking leads to the emergence of the spin plasmon, a novel collective excitation carrying both spin and charge character. In thin films, spin plasmons on opposite surfaces interact via Coulomb interactions, yielding coupled modes which are either pure spin or pure charge modes [3]. The momentum q of the optically excited plasmon can be tuned by varying the periodicity of the micro-ribbon array. This work presents far-infrared measurements of micro-ribbon arrays of thin films of the topological insulator Bi_2−xSb_xTe₃ grown on Al₂O₃. Plasmons hybridize with longitudinal phonons, resulting in excitations with a Fano lineshape [4]. By analysing the energy and lineshape as a function of the ribbon period, we study the character of the observed plasmonic excitations.

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