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arXiv · 2609.09497

Light-Driven Ultrafast Control of Time-Reversal Symmetry in SrTiO3

In Hyeok Choi·Sergei Urazhdin·Shivasheesh Varshney·Seung Gyo Jeong·Bharat Jalan·Keith A. Nelson
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Abstract

Light-driven control of material symmetry enables the engineering of phenomena forbidden in equilibrium. Although electromagnetic fields have been used to break time-reversal symmetry, its dynamic control on ultrafast timescales in nonmagnetic insulating oxides remains virtually unexplored. Here, we demonstrate simultaneous magnetic symmetry lowering and timereversal-symmetry breaking in cubic SrTiO3 driven by an off-resonant, elliptically polarized THz pulse. Second harmonic generation (SHG) polarimetry reveals emergent SHG circular dichroism inconsistent with third-order nonlinear processes under cubic m3m symmetry. The SHG polar patterns exhibit mirror-symmetry breaking, indicating a transient reduction to tetragonal 4/mm'm' magnetic symmetry. Furthermore, the SHG response scales linearly with the angular momentum of THz pulse, providing direct evidence for THz-field-induced timereversal-symmetry breaking. These results establish a direct pathway for ultrafast symmetry control in non-magnetic oxides, enabling dynamic manipulation of emergent phases on ultrafast timescales.

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In Hyeok Choi, Sergei Urazhdin, Shivasheesh Varshney, Seung Gyo Jeong, Bharat Jalan, Keith A. Nelson. 2026-09-08. Light-Driven Ultrafast Control of Time-Reversal Symmetry in SrTiO3. https://arxiv.org/abs/2609.09497

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