Berlin 2024 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 97: Focus Session: SrTiO₃: A Versatile Material from Bulk Quantum Paraelectric to 2D Superconductor II (joint session TT/KFM/MA/O)

O 97.8: Vortrag

Donnerstag, 21. März 2024, 17:00–17:15, H 0104

Mobility in SrTiO₃ Mediated by Machine Learning Predicted Anharmonic Phonons — •Luigi Ranalli¹, Carla Verdi², and Cesare Franchini¹ — ¹University of Vienna, Vienna, Austria — ²University of Queensland: Brisbane, Queensland, Australia

The anharmonic corrections to ionic motion play a crucial role in influencing the electron-phonon interaction, a phenomenon typically addressed through harmonic dynamical matrices at the ground state. By combining machine learning methodologies [1] and the stochastic self-consistent harmonic approximation [2], we achieve a precise depiction of the temperature-dependent evolution of phonon frequencies and the onset of ferroelectricity in the quantum paraelectric perovskites SrTiO₃ [3] and KTaO₃ [4]. In this presentation, anharmonic dynamical matrices are incorporated into the Boltzmann transport equation calculations for SrTiO₃ up to 300K using the EPW code [5] and fixing the derivatives of the Kohn-Sham potential computed through density functional perturbation theory [6]. This approach yields a coherent interaction vertex, ensuring that the temperature-dependent ferroelectric soft mode explains and recovers the observed trend in experimental mobility, akin to the behavior observed in KTaO₃.

[1] R. Jinnouchi et al., Phys. Rev. Lett. 122 (2019) 225701

[2] L. Monacelli et al., J. Phys.: Condens. Matter 33 (2021) 363001

[3] C. Verdi et al., Phys. Rev. Materials 7 (2023) L030801

[4] L. Ranalli et al., Adv. Quantum Technol. 6 (2023) 2200131

[5] H. Lee et al., 10.1038/s41578-021-00289-w (2023)