Poster

Probing deep interface electron-phonon interaction in Bi₂Te₃/GaAs with Brillouin scattering

M. Wiesner^1,2, A. Trzaskowska¹, B. Mroz^1,2, S. Charpentier³, S. Wang³, Y. Song³, F. Lombardi³, P. Lucignano⁴, G. Benedek^5,6, D. Campi⁵, M. Bernasconi⁵, F. Guinea⁷, and A. Tagliacozzo^8,4,9

¹Faculty of Physics, Adam Mickiewicz University, Umultowska 85, PL61614 Poznan, Poland

²The NanoBioMedical Centre, Adam Mickiewicz University, Umultowska 85, PL61614 Poznan, Poland

³Department of Microtechnology and Nanoscience, Chalmers University of Technology, SE-412 96 Göteborg, Sweden

⁴CNR-SPIN, Monte S. Angelo-Via Cintia, I-80126, Napoli, Italy

⁵Dipartimento di Scienza dei Materiali, Universitá di Milano-Bicocca, Via Cozzi 55, 20125 Milano, Italy

⁶Donostia International Physics Centre (DIPC), University of the Basque Country (UPV-EHU) Paseo Manuel de Lardizábal 4, 20018 Donostia/San Sebastian, Spain

⁷Instituto de Ciencia de Materiales de Madrid (CSIC), Sor Juana Inés de la Cruz 3, Madrid 28049, Spain

⁸Dipartimento di Fisica, Universitá di Napoli Federico II, Via Cintia, I-80126 Napoli, Italy

⁹INFN, Laboratori Nazionali di Frascati, Via E.Fermi, Frascati (Italy)

Brillouin light scattering from Rayleigh and Sezawa waves in 50-to-80 nm thick Bi₂Te₃ films on GaAs reveals Kohn anomalies for penetration lengths matching the interface space-charge region. Besides demonstrating important electron-phonon coupling effects in the GHz frequency domain, the experiment shows that information on deep interface fermions can be obtained by tuning the penetration of optically-generated surface phonons, as in a sort of quantum sonar. Density functional perturbation theory (DFPT) calculations for the most probable interface structure, modeled by one quintuple Bi₂Te₃ on a GaAs(001) substrate passivated by an additional Te wetting layer, allow to elucidate the structure of the space charge and to explain the source of the interface electron-phonon coupling and of the observed anomalies.