Anisotropic attosecond charge carrier dynamics and layer decoupling in quasi-2D layered SnS2. Issue 1 (December 2017)

• Record Type: Journal Article
• Authors: Eads, Calley; Bandak, Dmytro; Neupane, Mahesh; Nordlund, Dennis; Monti, Oliver
• Is Part Of: Nature communications. Volume 8:Issue 1(2017)
• Page Start: 1
• Page End: 7
• Publication Date: 2017-12
• Subjects: Biology -- Periodicals; Physical sciences -- Periodicals; 505
• DOI: 10.1038/s41467-017-01522-3
• Languages: English
• ISSNs: 2041-1723

Abstract

Abstract Strong quantum confinement effects lead to striking new physics in two-dimensional materials such as graphene or transition metal dichalcogenides. While spectroscopic fingerprints of such quantum confinement have been demonstrated widely, the consequences for carrier dynamics are at present less clear, particularly on ultrafast timescales. This is important for tailoring, probing, and understanding spin and electron dynamics in layered and two-dimensional materials even in cases where the desired bandgap engineering has been achieved. Here we show by means of core–hole clock spectroscopy that SnS2 exhibits spin-dependent attosecond charge delocalization times (τ deloc ) for carriers confined within a layer, τ deloc < 400 as, whereas interlayer charge delocalization is dynamically quenched in excess of a factor of 10, τ deloc > 2.7 fs. These layer decoupling dynamics are a direct consequence of strongly anisotropic screening established within attoseconds, and demonstrate that important two-dimensional characteristics are also present in bulk crystals of van der Waals-layered materials, at least on ultrafast timescales. Owing to their layered nature, transition metal dichalcogenides possess an anisotropic electronic structure whose impact on carrier dynamics is not fully known. Here, the authors use X-ray spectroscopy to unveil the electronic coupling and attosecond dynamics in SnS2, a prototypical van der Waals layered crystal.