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Title: Phonon renormalization and Raman spectral evolution through amorphous to crystalline transitions in Sb{sub 2}Te{sub 3} thin films

A symmetry specific phonon mode renormalization is observed across an amorphous to crystalline phase transformation in thin films of the topological material Sb{sub 2}Te{sub 3} using Raman spectroscopy. We present evidence for local crystalline symmetry in the amorphous state, eventhough, the q = 0 Raman selection rule is broken due to strong structural disorder. At crystallization, the in-plane polarized (E{sub g}{sup 2}) mode abruptly sharpens while the out-of-plane polarized (A{sub 1g}) modes are only weakly effected. This effect unique to the E{sub g} symmetry is exceptional considering that polarized spectra and comparison of the single phonon density of states between the amorphous and crystalline phases suggest that short range order of the amorphous phase is, on the average, similar to that of the crystalline material while electrical transport measurements reveal a sharp insulator-to-metal transition. Our findings point to the important role of anisotropic disorder affecting potential applications of topological and phase-change based electronics.
Authors:
; ;  [1] ;  [2] ; ;  [3] ;  [4]
  1. The Graduate Center, CUNY, New York, New York 10016 (United States)
  2. (United States)
  3. Department of Physics, The City College of New York, CUNY, New York, New York 10031 (United States)
  4. IBM T. J. Watson Research Center, Yorktown Heights, New York 10598 (United States)
Publication Date:
OSTI Identifier:
22300079
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Physics Letters; Journal Volume: 104; Journal Issue: 22; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; AMORPHOUS STATE; ANISOTROPY; ANTIMONY TELLURIDES; CRYSTALLIZATION; METALS; PHONONS; RAMAN SPECTRA; RENORMALIZATION; SELECTION RULES; SPECTRA; SYMMETRY; THIN FILMS