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This content will become publicly available on March 21, 2017

Title: Phonon anomalies in some iron telluride materials

In this paper, the detailed temperature dependence of the infrared-active mode in Fe1.03Te (TN ≃ 68 K) and Fe1.13Te (TN ≃ 56 K) has been examined, and the position, width, strength, and asymmetry parameter have been determined using an asymmetric Fano profile superimposed on an electronic background. In both materials the frequency of the mode increases as the temperature is reduced; however, there is also a slight asymmetry in the line shape, indicating that the mode is coupled to either spin or charge excitations. Below TN there is an anomalous decrease in frequency, and the mode shows little temperature dependence, at the same time becoming more symmetric, suggesting a reduction in spin- or electron-phonon coupling. The frequency of the infrared-active mode and the magnitude of the shift below TN are predicted reasonably well by first-principles calculations; however, the predicted splitting of the mode is not observed. In superconducting FeTe0.55Se0.45 (Tc ≃ 14 K) the infrared-active Eu mode displays asymmetric line shape at all temperatures, which is most pronounced between 100 – 200 K, indicating the presence of either spin- or electron-phonon coupling, which may be a necessary prerequisite for superconductivity in this class of materials.
Authors:
;  [1] ;  [1] ;  [1] ;  [1]
  1. Brookhaven National Lab. (BNL), Upton, NY (United States)
Publication Date:
OSTI Identifier:
1255725
Report Number(s):
BNL--112206-2016-JA
Journal ID: ISSN 2469-9950; PRBMDO; R&D Project: PO016; PO010; KC0202020; KC0201060
Grant/Contract Number:
SC0012704
Type:
Accepted Manuscript
Journal Name:
Physical Review B
Additional Journal Information:
Journal Volume: 93; Journal Issue: 12; Journal ID: ISSN 2469-9950
Publisher:
American Physical Society (APS)
Research Org:
Brookhaven National Laboratory (BNL), Upton, NY (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY