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Photoinduced multistage phase transitions in Ta2NiSe5
1International Center for Quantum Materials, School of Physics, Peking University, Beijing, China.
Nature Communications
|April 7, 2021
Summary
Researchers achieved a long-lived insulator-to-metal phase transition in Ta2NiSe5 using ultrafast laser pulses. This photoinduced state is stable up to 350 K, showing potential for novel electronic devices.
Area of Science:
- Condensed matter physics
- Materials science
- Ultrafast phenomena
Background:
- Controlling material properties with light is key for advanced electronics.
- Achieving long-lived photoinduced electronic states, especially insulator-to-metal transitions, remains challenging.
Purpose of the Study:
- To investigate photoinduced phase transitions in Ta2NiSe5.
- To explore the possibility of creating long-lived, light-induced electronic states.
Main Methods:
- Combines transport measurements, ultrashort photoexcitation, and coherent phonon spectroscopy.
- Utilizes transmission electron microscopy (TEM) to analyze structural changes.
- Employs nano-sheet samples with thickness below the optical penetration depth.
Main Results:
- Photoexcitation induces multistage phase transitions in Ta2NiSe5.
- A threshold excitation intensity triggers a stable, photoinduced metallic state.
- Resistivity drops by over four orders of magnitude at 50 K.
- The new state is thermally stable up to 350 K with a unique lattice structure.
- TEM reveals in-chain Ta atom displacement in the photoinduced phase.
Conclusions:
- Ultrafast photoexcitation can drive Ta2NiSe5 into a long-lived, metallic state.
- This photoinduced state exhibits distinct structural and electronic properties.
- Sample thickness is critical for achieving complete photoinduced transitions.
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