Ultrafast electron localization and screening in a transition metal dichalcogenide

Abstract

The coupling of light to electrical charge carriers in semiconductors is the foundation of many technological applications. Attosecond transient absorption spectroscopy measures simultaneously how excited electrons and the vacancies they leave behind dynamically react to the applied optical fields. In compound semiconductors, these dynamics can be probed via any of their atomic constituents. Often, the atomic species forming the compound contribute comparably to the relevant electronic properties of the material. One therefore expects to observe similar dynamics, irrespective of the choice of atomic species via which it is probed. Here, we show in the two-dimensional transition metal dichalcogenide semiconductor $MoS{e}_2$, that through a selenium-based transition we observe charge carriers acting independently from each other, while when probed through molybdenum, the collective, many-body motion of the carriers dominates. Such unexpectedly contrasting behavior can be traced back to a strong localization of electrons around molybdenum atoms following absorption of light, which modifies the local fields acting on the carriers. We show that similar behavior in elemental titanium metal carries over to transition metal-containing compounds and is expected to play an essential role for a wide range of such materials. Knowledge of independent particle and collective response is essential for fully understanding these materials.

30 pages, 11 figures

References in corpus (5)

• Breakdown of the Dipole Approximation in Strong-Field Ionization
• Direct Determination of Band Gap Renormalization in Photo-Excited Monolayer MoS2
• Electronic Band Structure of Transition Metal Dichalcogenides from Ab Initio and Slater-Koster Tight-Binding Model
• Coupled Valence Carrier and Core-Exciton Dynamics in WS${}_2$ Probed by Few-Femtosecond Extreme Ultraviolet Transient Absorption Spectroscopy
• Ultrafast electron localization and screening in a transition metal dichalcogenide

Cited by in corpus (4)

• Ultrafast electron localization and screening in a transition metal dichalcogenide
• Coherently Coupled Carrier and Phonon Dynamics in Elemental Tellurium Probed by XUV Transient Absorption
• First-principles approach to ultrafast pump-probe spectroscopy in solids
• High-purity valley-polarized currents induced by bichromatic optical fields in two-dimensional materials