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Title: Confined lattice dynamics of single and quadruple SnSe bilayers in [(SnSe) 1.04 ] m [MoSe 2 ] n ferecrystals

The Sn specific densities of phonon states in the SnSe subunits of [(SnSe) 1.04] m[MoSe 2] n ferecrystals with (m,n) = (1,1), (4,1) and in bulk SnSe were derived from nuclear inelastic scattering by the 119Sn M ssbauer resonance. When using different measurement configurations, phonons with polarization parallel and perpendicular to the ferecrystal plane were specifically probed. Vibrational properties and phonon spectral weight are found to strongly depend on the phonon polarization and layer count m. Moreover, a highly peculiar feature of these ferecrystal densities of phonon states is the emergence of rather sharp high energy vibrational modes polarized perpendicular to the ferecrystal plane, which contrasts with usual findings in thin layered structures and nanostructured materials in general, and a depletion of modes with a gap appearing between acoustic and high energy modes. The spectral weight of these phonons depends on the overall SnSe content, m, but cannot be unambiguously attributed to SnSe MoSe 2 interfaces. Considering the low energy part of lattice dynamics, ferecrystals exhibit rather low average phonon group velocities as compared to the speed of sound in the long wavelength limit. For the (1,1) ferecrystal, this effect is most pronounced for vibrations polarized in the ferecrystal plane.more » Therefore, an experimental microscopic origin for the vibrational and bonding anisotropy in subunits of ferecrystals is provided.« less
 [1] ;  [2] ;  [3] ;  [4] ;  [5]
  1. Julich Research Centre (Germany)
  2. Argonne National Lab. (ANL), Argonne, IL (United States)
  3. Oregon Inst. of Technology, Klamath Falls, OR (United States)
  4. Univ. of Oregon, Eugene, OR (United States)
  5. Julich Research Centre (Germany); Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Publication Date:
Grant/Contract Number:
AC05-00OR22725; AC02-06CH11357; DMR-1266217; VH-NG407
Accepted Manuscript
Journal Name:
Additional Journal Information:
Journal Volume: 8; Journal Issue: 2; Journal ID: ISSN 2040-3364
Royal Society of Chemistry
Research Org:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22); National Science Foundation (NSF); Helmholtz Gemeinschaft Deutscher Forschungszentren; German Research Foundation (DFG)
Country of Publication:
United States
OSTI Identifier:
Alternate Identifier(s):
OSTI ID: 1339552