SPICE Workshop on Chiral Phonons, July 29th - 31st 2025
Rossitza Pentcheva
Recent experimental studies indicate electric-field-driven ferroelectricity [1] and multiferroicity [2] in the paradigmatic nonmagnetic band insulator SrTiO3 in the terahertz regime. Following a comprehensive study of the optical [3] and x-ray absorption [4] spectra including quasiparticle and excitonic effects, here we explore the response of SrTiO3 to laser excitation. Using real-time time-dependent density functional theory (RT-TDDFT) as implemented in the elk code we investigate both linear and circular polarized laser pulses and vary systematically the laser frequency and fluence. A complex site- and orbital-dependent temporal dynamics is observed with opposite sign of fluctuations at O and Ti sites and charge transfer from O 2p to Ti 3d states for linearly polarized light, that breaks dynamically inversion symmetry. Notably, circularly polarized pulses induce a finite transient magnetic moment of up to 0.1μB at the Ti sites which is absent for linearly polarized pulses. We assess the origin of the induced magnetization.
[1] T.F. Nova et al., Science 364, 1075 (2019)[2] M. Basini et al., Nature 628, 534 (2024).
[3] V. Begum, M.E. Gruner and R. Pentcheva, Phys. Rev. Mater. 3, 065004 (2019),
[4] V. Begum-Hudde et al., Phys. Rev. Res. 5, 013199 (2023).
Funding by DFG within CRC1242 (project C02) and computational time at magnitUDE, amplitUDE and the Leibniz Supercomputer Center (project pr87ro) are gratefully acknowledged.