Interplay between phonons and topology in adiabatic and non-adiabatic regimes

Datum

06.10.2026

Zeit

10:00 - 11:00

Sprecher

Dr. Paolo Fachin

Zugehörigkeit

Sapienza-University of Rome

Sprache

en

Hauptthema

Materialien

Host

Grit Rötzer

Beschreibung

In this talk, we investigate the interplay between the vibrational properties and the electronic topology. In the Haldane and Kane-Mele models, prototypical 2D topological insulators realised on a honeycomb lattice, this relation arises from the connection between the vibrational and electronic responses at the band edges [1]. In the time-reversal symmetry-breaking Haldane model, the splitting of the optical phonons into two circularly polarised modes of opposite handedness is significantly enhanced in the topologically non-trivial state. Furthermore, in both the Haldane and the time-reversal-symmetric Kane-Mele model, the vibrational infrared activity exhibits large changes across the topological transition. These results enable the interpretation of the first-principles vibrational infrared spectra of germanene and jacutingaite [2], recently investigated Kane-Mele materials. The connection between electronic topology and vibrational properties also holds under non-adiabatic conditions [2,3], where a proper assessment of the responses requires the use of a nuclear-velocity-including atomic orbital basis in the construction of effective models [3,4,5]. [1] P. Fachin, F. Macheda, P. Barone and F. Mauri, Phys. Rev. B,110, L201405 (2024). [2] P. Fachin, F. Macheda, P. Barone and F. Mauri, npj Comp. Mat., 11, 307 (2025) [3] P. Fachin, F. Macheda, P. Barone and F. Mauri, arXiv 2607.20117 (2026) [4] P. Fachin, F. Macheda, P. Barone and F. Mauri, Phys. Rev. B 114, 134302 (2026) [5] M. Stengel, M. Royo, and E. Artacho, Phys. Rev. Lett. 136, 196401, 2026 .

Links

• Seminars at the IFW

Letztmalig verändert: 06.10.2026, 07:39:50