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Excitonic Hamiltonians for Calculating Optical Absorption Spectra and Optoelectronic Properties of Molecular Aggregates and Solids
Published on: May 27, 2020
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Light-induced dimension crossover dictated by excitonic correlations.
Yun Cheng1,2, Alfred Zong3,4, Jun Li5
1Key Laboratory for Laser Plasmas (Ministry of Education), School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai, 200240, China.
Nature Communications
|February 19, 2022
Summary
Applying ultrashort laser pulses to 1T-TiSe2 reveals how electronic correlations control dimensionality. Photoexcitation breaks excitonic pairs, transforming the 3D charge-density-wave into a 2D state, controlling emergent phases.
Area of Science:
- Condensed Matter Physics
- Materials Science
- Ultrafast Spectroscopy
Background:
- Strongly correlated electron systems exhibit exotic phases when dimensionality is reduced.
- Charge-density-wave (CDW) states are sensitive to electronic interactions and dimensionality.
- Exciton condensation in 1T-TiSe2 influences its CDW properties.
Purpose of the Study:
- Investigate the role of dimensionality and many-body correlations in non-adiabatic transitions.
- Determine how optical manipulation affects the dimensionality of CDW states in 1T-TiSe2.
- Clarify the influence of excitonic correlations on CDW coherence.
Main Methods:
- Ultrafast laser spectroscopy on 1T-TiSe2.
- Time-resolved measurements of charge-density-wave dynamics.
- Analysis of electron-hole interactions and their impact on structural transitions.
Main Results:
- Photoexcitation suppresses the equilibrium 3D CDW state.
- A non-equilibrium 2D CDW state is generated upon photoexcitation.
- Dimensionality reduction to 2D CDW is contingent on breaking bound electron-hole pairs (excitons).
Conclusions:
- Excitonic correlations are crucial for maintaining out-of-plane CDW coherence.
- Optical control of electronic interactions can tune the dimensionality of broken-symmetry orders.
- This work provides a pathway for realizing novel emergent states in correlated materials.
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