2025/05/26 by Luis Enrique Parra López, Quan, Jingkai, López, Luis E. Parra +11 · 2 citations
Engineering · Materials Science · #FOS: Physical sciences #Machine Learning in Materials Science #Materials Science (cond-mat.mtrl-sci) #Mesoscale and Nanoscale Physics (cond-mat.mes-hall) #Molecular Junctions and Nanostructures #Organic and Molecular Conductors Research #Strongly Correlated Electrons (cond-mat.str-el)
paper · pdf · doi:10.48550/arxiv.2505.20541
openalex publication_date 2025/05/26 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/01
Controlling quantum materials with ultrafast light pulses enables access to transient and metastable states that are inaccessible under equilibrium conditions. Yet their local dynamics remain poorly understood due to the challenge of resolving ultrafast processes with angstrom-scale spatial resolution. Here, we use terahertz scanning tunnelling microscopy (THz-STM) to probe coherent collective dynamics within a THz-induced metastable state in the layered charge density wave (CDW) material 1T-TaS2. Following ultrafast photoexcitation, we locally resolve coherent oscillations of the CDW amplitude mode at 2.5 THz together with two previously unreported modes at 1.3 THz and 0.7 THz. Comparison with phonon calculations identifies these as interlayer breathing and shear vibrations that are sensitive to the stacking configuration. These coherent dynamics are observed within a THz-induced metastable state that exhibits long-lived and spatially inhomogeneous modifications of the local density of states within the insulating gap, while higher THz fields drive a local redistribution and disordering of Star-of-David clusters near defects and domain boundaries. Our results suggest that the THz-induced metastable state involves a modification of the local interlayer stacking configuration, and demonstrate the role of interlayer degrees of freedom in the ultrafast dynamics of light-induced phases in layered quantum materials.