Transient Terahertz Oscillations During Photoinduced Polarization Topology Reconfiguration in Ferroelectric Superlattices

Journal Article · Sat Nov 01 00:00:00 EDT 2025 · Advanced Science

DOI:https://doi.org/10.1002/advs.202522387· OSTI ID:3011729

Sri Gyan, Deepankar ^[1]; Lee, Hyeon Jun ^[1]; Guo, Xiangwei ^[1]; Ahn, Youngjun ^[2]; Marks, Samuel ^[2]; Yusuf, Mohammed ^[3]; Dawber, Matthew ^[4]; Glownia, James ^[5]; Zhu, Diling ^[5]; Sato, Takahiro ^[5]; Song, Sanghoon ^[5]; Wen, Haidan ^[6]; Hu, Jia-Mian ^[1]; Evans, Paul ^[1]

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1. Univ. of Wisconsin, Madison, WI (United States)
2. Univ. of Wisconsin, Madison, WI (United States); Argonne National Laboratory (ANL), Argonne, IL (United States)
3. Stony Brook Univ., NY (United States)
4. Univ. of Vermont, Burlington, VT (United States)
5. SLAC National Accelerator Laboratory (SLAC), Menlo Park, CA (United States)
6. Argonne National Laboratory (ANL), Argonne, IL (United States)

Terahertz resonances embedded in crystalline heterostructures could close a spectral gap between conventional electronics and photonics while opening new windows on non-equilibrium lattice dynamics. We show that femtosecond optical screening of the depolarization field in epitaxial PbTiO3/SrTiO3 superlattices launches a collective polar mode that oscillates near 1 THz and coherently spans the entire mini-Brillouin zone. Wave-vector-resolved pump–probe X-ray diffraction resolves a nearly dispersion-less oscillation at 0.87 THz and 0.94 THz at the zone boundary and zone center, respectively, persisting for ~2.5 ps, corresponding to a weakly damped resonance. Dynamical phase-field simulations reveal the origin of the mode to mesoscopic rotation of closure-domain textures during the photo-excited transition from an unscreened to a screened electrostatic state. Varying the PbTiO3 and SrTiO3 ratio tunes the mode frequency continuously from 0.9 to 1.4 THz, providing a quantitative design rule for frequency-selectable THz oscillators in ferroelectric heterostructures. By coupling nanoscale polarization reconfiguration to long-wavelength coherent dynamics, this work establishes depolarization-field engineering to topology-driven THz functionality and expanding the landscape of collective lattice dynamics.

• Research Organization: Board of Regents of the University of Wisconsin System, operating as University of Wisconsin-Madison
• Sponsoring Organization: USDOE Office of Science (SC), Basic Energy Sciences (BES). Materials Sciences & Engineering Division (MSE)
• Grant/Contract Number: FG02-04ER46147
• OSTI ID: 3011729
• Journal Information: Advanced Science, Journal Name: Advanced Science
• Country of Publication: United States
• Language: English