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Abstract

Understanding ultrafast carrier dynamics is crucial for revealing many-body interactions and emergent phenomena in quantum materials. Time-resolved angle-resolved photoemission spectroscopy (Tr-ARPES) is considered a powerful technique for probing non-equilibrium electronic processes with high temporal and momentum resolution. Recent advancements in high harmonic generation (HHG)-based ultrafast spectroscopy have enabled precise investigations of carrier relaxation pathways in layered materials.
Fluence-dependent electronic relaxation pathways in graphite have been observed, bridging static and dynamic quasi-equilibrium states. The results highlight the interplay between electron-electron and electron-phonon interactions in dictating carrier relaxation timescales.
Furthermore, the charge density wave (CDW) phase transition in TiSe2 has been explored, revealing orbital-selective carrier relaxation and effective mass renormalization. The findings suggest that transition metal d-states play a significant role in CDW formation, while transient band structure analysis under varying excitation fluences provides evidence for a multi-stage CDW melting and recovery process.
These findings contribute to a broader understanding of phase transitions and non-equilibrium quantum states in strongly correlated materials. The capabilities of Tr-ARPES in uncovering fundamental interactions in layered quantum materials underscore its potential for advancing ultrafast phase control in condensed matter systems.