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TT: Fachverband Tiefe Temperaturen

TT 55: Topology and Symmetry Protected Materials (joint session O/TT)

TT 55.4: Talk

Wednesday, March 20, 2024, 15:45–16:00, HL 001

Carrier Injection Observed by Interface-Enhanced Raman Scattering from Topological Insulators on Gold Substrates. — Sarah Scheitz, Tomke Eva Glier, Christian Nweze, •Malte Felix van Heek, Isa Moch, Robert Zierold, Robert Blick, Nils Huse, and Michael Rübhausen — Institute of Nanostructure and Solid-State Physics, University of Hamburg, Hamburg, 22761, Germany

The electron-phonon interaction at the interface between topological insulator (TI) of bismuth/tellurium and gold substrate as a function of TI nanoflakes thickness is studied with a sub-micron Raman spectroscopy. We show the presence of interface-enhanced Raman Scattering and strong phonon renormalization induced by carriers injected from the gold substrate into the topological surface in contact with the gold substrate. The associated electron-phonon coupling shows an approximate linear behavior as function of nanoflake thickness. The strongly nonlinear change of the Raman scattering cross-section as a function of flake thickness can be associated with band bending effects at the metal-TI interface. This provides spectroscopic evidence for strongly modified band structure in the first few quintuple layers of bismuth selenide and tellurium selenide TI.

Keywords: Topological insulator gold contact; Bismuth chalcogenides; Raman Spectroscopy; Carrier injection; Electron phonon coupling