We combine advanced X-ray scattering, theoretical modeling, and machine learning to uncover how nanoscale structure shapes material properties.
Our research spans polar vortices and skyrmions, ultrafast lattice dynamics, and probabilistic structure analysis—connecting structure, dynamics, and function.
RESEARCH AREAS
Ultrafast Dynamics & Nanoscale Strain Waves
We combine time-resolved pump–probe X-ray scattering and diffraction with dynamical phase-field simulations to investigate the interplay between polarization textures and lattice deformation. A particular focus is how the spatially periodic piezoelectric response of polar vortices acts as an acoustic diffraction grating. Through this work, we uncover mechanisms for generating strain waves with nanoscale wavefronts and sub-terahertz frequencies, and explore opportunities to control acoustic waves using polar topological textures. Key Topics: Ultrafast X-ray measurements · Polarization–lattice coupling · Piezoelectric response · Nanoscale acoustic waves Selected Publication: Nature Physics (2026)
Polar Topological Textures & Chirality
We investigate the three-dimensional structures and chirality of polar vortices and skyrmions in ferroelectric superlattices. Combining resonant elastic X-ray scattering with quantitative scattering theory, we resolve complex electric polarization textures. We also employ polarization-constrained phase-field modeling to explore the mechanisms governing the formation of distinct chiral structures and phases. Key Topics: Polar vortices and skyrmions · Structural chirality · Resonant X-ray scattering · Phase-field modeling Selected Publications: Nature Communications (2022) · Physical Review Letters (2022) · Nano Letters (2025)
AI-Assisted X-ray Analysis & Probabilistic Structure Inference
We develop machine-learning methods to rapidly and reliably extract thin-film structural information from X-ray measurements. Using Gaussian mixture density networks, we estimate layer thicknesses, densities, and interface roughnesses probabilistically, providing uncertainty estimates and multiple candidate solutions alongside best-fit values. This approach addresses the inverse problem in which different structures can produce similar scattering signals, improving the reliability of quantitative structural analysis. Key Topics: Machine learning · X-ray reflectivity analysis · Uncertainty quantification · Inverse problems Selected Publication: Journal of Applied Crystallography (2021)
Ultrafast Dynamics & Nanoscale Strain Waves
Polar Topological Textures & Chirality
AI-Assisted X-ray Analysis & Probabilistic Structure Inference
FEATURED RESEARCH
NATURE PHYSICS · COVER ARTICLE
Nanoscale Strain Wave Generation by a Piezoelectric Grating from Polar Vortices Nature Physics · 2026 Understanding nanoscale strain-wave generation arising from polar vortex structures.
PHYSICAL REVIEW LETTERS · COVER PAPER
Structural Chirality of Polar Skyrmions Probed by Resonant lastic X-Ray Scattering Physical Review Letters 129, 247601 (2022)
Publications
Professor
Professor
Department of Physics, Soongsil University
Seoul 06978, Korea
Tel) +82-2-820-0401
Email: drlee@ssu.ac.kr
Education
- Ph.D. in Physics, 1999: POSTECH(Pohang University of Science and Technology), Korea
Advisor: Professor Ki-Bong Lee
- MS in Physics, 1995: POSTECH, Korea.
- BS in Physics, 1993: Seoul National University, Korea.
Professional Experience
- Professor : September 2008 – Present,
- Research Scientist : February 2006 - August 2008
- Assistant Physicist : August 2002 - February 2006
- Postdoctoral : August 1999 - August 2002
XFEL Science Team
X-ray Free Electron Laser, Pohang Accelerator Laboratory
836 Jigok-dong, Nam-gu, Pohang-si, Gyeongsangbuk-do
REPUBLIC OF KOREA
E kooktae@postech.ac.kr
Education
- Ph.D. in Physics, 2023: Soongsil University, Korea
X-선 공명 탄성 산란을 이용한 강유전체의 극성 카이랄 구조 연구
(A study on the polar chiral structure of ferroelectrics using resonant elastic x-ray scattering)
Advisor: Professor Dong Ryeol Lee
- BS in Physics, 2017: Soongsil University, Seoul
Professional Experience
- Staff Scientist (2026-present)
- Postdoc, Soongsil University, Seoul (2023 - 2026)
- Postdoc, POSTECH, Gyeongsangbuk-do (2024 - 2025)
