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TT: Fachverband Tiefe Temperaturen

TT 62: Focus Session: SrTiO₃: A Versatile Material from Bulk Quantum Paraelectric to 2D Superconductor I (joint session TT/KFM/MA/O)

TT 62.3: Invited Talk

Thursday, March 21, 2024, 10:30–11:00, H 0104

Polarons and Excitons in quantum-paraelectric SrTiO₃ — •Cesare Franchini — University of Vienna & Bologna

SrTiO₃ stands as one of the most extensively investigated materials, captivating attention due to its distinctive electronic properties emerging from its quantum paraelectric nature. Positioned on the cusp of various collective phases, this material holds significant potential for exploitation in electronic and optical applications. In this presentation, we delve into the biphonon collective behaviors and quasiparticle properties of SrTiO₃ in both bulk and reduced dimensions, leveraging a combination of single-particle and many-body methods supported by machine learning techniques. Our exploration commences with an examination of temperature-dependent quantum and anharmonic effects employing a synergy of machine-learned potentials and the stochastic self-consistent harmonic approximation [1,2]. Shifting focus, we investigate the electron-phonon-driven formation of polarons, scrutinizing the interplay between spatially localized small polarons and dispersive large polarons in both bulk SrTiO₃ [3,4] and on the bulk-terminated SrTiO₃(001) surface [5,6]. In conclusion, our study delves into the optical and excitonic properties, with particular emphasis on the emergence of strongly bound excitonic peaks in the monolayer limit [7,8].

[1] Adv. Quantum Technol. 6 (2023) 2200131

[2] Phys. Rev. Mater. 7 (2023) L030801

[3] Phys. Rev. B 91 (2015) 085204

[4] npj Computational Materials 125 (2022)

[5] Phys. Rev. Mater. 3, 034407 (2019); Phys. Rev. B 103 (2021) L241406

[6] Phys. Rev. Mater. 7 (2023) 064602

[7] Phys. Rev. Mater. 5 (2021) 074601

[8] arXiv:2303.14830