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Updated: Oct 9, 2025
11:21
Cooling an Optically Trapped Ultracold Fermi Gas by Periodical Driving
Published on: March 30, 2017
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Inducing thermodynamically blocked atomic ordering via strongly driven nonequilibrium kinetics
Chulho Jung1,2, Yungok Ihm2,3, Do Hyung Cho1,2
1Department of Physics, POSTECH, Pohang 37673, Korea.
Science Advances
|December 22, 2021
Summary
Scientists used ultrafast lasers to observe hidden material phases in bismuth nanoparticles. This nonequilibrium process revealed kinetically controlled surface ordering, demonstrating a new route for material discovery.
Area of Science:
- Materials Science
- Condensed Matter Physics
- Ultrafast Phenomena
Background:
- Ultrafast light-matter interactions can access novel material phases via nonequilibrium kinetics.
- Understanding intermediate states in driven systems is crucial for material discovery but remains limited.
Purpose of the Study:
- To investigate intermediate states in photoexcited bismuth nanoparticles using ultrafast time-resolved imaging.
- To explore the role of electron-mediated free-energy modification in inducing exotic material phases.
Main Methods:
- Single-pulse time-resolved imaging utilizing X-ray Free-Electron Lasers (XFELs).
- Molecular dynamics simulations to analyze observed kinetic pathways.
Main Results:
- Observed kinetically reversed surface ordering in photoexcited bismuth nanoparticles during ultrafast melting.
- Identified an entropy-lowering reaction that is thermodynamically inaccessible in equilibrium.
- Demonstrated electron-mediated ultrafast free-energy modification as key to inducing exotic phases.
Conclusions:
- Ultrafast photoexcitation of electrons offers an efficient strategy to access hidden material phases.
- Nonequilibrium reaction pathways can overcome thermodynamic barriers, enabling the discovery of new material properties.
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