Flat Club - Claude Monney, Uni Fribourg

01.10.2024 12:30 – 14:00

Transient topological state in a polar crystal
Claude Monney, Uni Fribourg

The translational symmetry of the ionic potential in a crystal results in a periodic electronic structure in momentum space. Analogously, the periodic electric field of an intense light pulse can create replica of electronic states. These so-called Floquet state are shifted in energy by the photon frequency [1]. During the last decade, a few examples of the generation of Floquet states have been revealed using time-resolved angle-resolved photoemission spectroscopy (ARPES) [2,3]. In these works, band gap opening at the crossing between the Floquet states and the original electronic states have been observed as a consequence of strong light-matter interaction. In that framework, Lindner and coworkers have proposed to use Floquet states to engineer a transient topological state with light pulses [4].
In this talk, I will present our recent study of the semiconductor SnTe, for which the occurrence of topological surface states is intimately linked to a polar structural phase transition [5]. First, I will show static ARPES data acquired as a function temperature. Our excellent experimental resolution and unprecedented thin film quality allow us to follow the evolution of the Rashba splitting induced by the structural distortion in the bulk bands, revealing substantial deviations from a mean-field-like transition [6]. In a second part, I will elaborate on the implications of our results for the topological nature of the surface states in SnTe. Using time-resolved ARPES data, I will then show how tailored light pulses can be used to photoinduce a transient topological state in SnTe in the absence of any significant structural change. I will argue that a strong light-matter interaction “à la Floquet” is the relevant mechanism.

References:
[1] S. Ito, M. Schüler, M. Meierhofer, S. Schlauderer, J. Freudenstein, J. Reimann, D. Afanasiev, K. A. Kokh, O. E. Tereshchenko, J. Güdde, M. A. Sentef, U. Höfer and R. Huber, 616, 696 (2023).
[2] F. Mahmood, C. Chan, Z. Alpichshev, D. Gardner, Y. Lee, P. A. Lee and N. Gedik, Nature Physics 12, 306 (2016).
[3] S. Zhou, C. Bao, B. Fan, F. Wang, H. Zhong, H. Zhang, P. Tang, W. Duan and S. Zhou, Phys. Rev. Lett. 131, 116401(2023).
[4] N. H. Lindner, G. Refael and V. Galitski, Nature Physics 7, 490 (2011).
[5] E. Plekhanov, P. Barone, D. Di Sante and S. Picozzi, Phys. Rev. B 90, 161108(R) (2014).
[6] F. Chassot, A. Pulkkinen, G. Kremer, T. Zakusylo, G. Krizman, M. Hajlaoui, J. H. Dil, J. Krempasky, J. Minar, G. Springholz and C. Monney, Nano Letters 24, 82 (2024).

Lieu

Bâtiment: Ecole de Physique

Auditoire Stueckelberg
Pizza: 12:30, Start discussion: 13:00

entrée libre