Spin fluctuations and superconductivity in powders of Fe 1+xTe 0.7Se 0.3 as a function of interstitial iron concentration

Stock, C., Rodriguez, E.E., Green, M.A. (2012) Spin fluctuations and superconductivity in powders of Fe 1+xTe 0.7Se 0.3 as a function of interstitial iron concentration. Physical Review B - Condensed Matter and Materials Physics, 85 (9). p. 94507. ISSN 10980121 (ISSN). (doi:10.1103/PhysRevB.85.094507) (The full text of this publication is not currently available from this repository. You may be able to access a copy if URLs are provided)

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Abstract

Using neutron inelastic scattering, we investigate the role of interstitial iron on the low-energy spin fluctuations in powder samples of Fe 1+xTe 0.7Se 0.3. We demonstrate how combining the principle of detailed balance along with measurements at several temperatures allows us to subtract both temperature-independent and phonon backgrounds from S(Q,Ï?) to obtain purely magnetic scattering. For small values of interstitial iron [x=0.009(3)], the sample is superconducting (T c=14 K) and displays a spin gap of 7 meV peaked in momentum at wave vector q 0=(Ï?,Ï?) consistent with single-crystal results. On populating the interstitial iron sites, the superconducting volume fraction decreases and we observe a filling in of the low-energy magnetic fluctuations and a decrease of the characteristic wave vector of the magnetic fluctuations. For large concentrations of interstitial iron [x=0.048(2)] where the superconducting volume fraction is minimal, we observe the presence of gapless spin fluctuations at a wave vector of q 0=(Ï?,0). We estimate the absolute total moment for the various samples and find that the amount of interstitial iron does not change the total magnetic spectral weight significantly, but rather has the effect of shifting the spectral weight in Q and energy. These results show that the superconducting and magnetic properties can be tuned by doping small amounts of iron and are suggestive that interstitial iron concentration is also a controlling dopant in the Fe 1+xTe 1-ySe y phase diagram in addition to the Te/Se ratio. © 2012 American Physical Society.

Item Type: Article
DOI/Identification number: 10.1103/PhysRevB.85.094507
Additional information: Unmapped bibliographic data: C7 - 094507 [EPrints field already has value set] LA - English [Field not mapped to EPrints] J2 - Phys. Rev. B Condens. Matter Mater. Phys. [Field not mapped to EPrints] AD - NIST Center for Neutron Research, 100 Bureau Drive, Gaithersburg, MD 20899, United States [Field not mapped to EPrints] AD - Indiana University, 2401 Milo B. Sampson Lane, Bloomington, IN 47404, United States [Field not mapped to EPrints] AD - Department of Materials Science and Engineering, University of Maryland, College Park, MD 20742, United States [Field not mapped to EPrints] DB - Scopus [Field not mapped to EPrints]
Subjects: Q Science > QC Physics > QC173.45 Condensed Matter
Q Science > QD Chemistry > QD478 Solid State Chemistry
Divisions: Faculties > Sciences > School of Physical Sciences > Functional Materials Group
Depositing User: Giles Tarver
Date Deposited: 14 Oct 2015 11:29 UTC
Last Modified: 29 May 2019 16:08 UTC
Resource URI: https://kar.kent.ac.uk/id/eprint/50968 (The current URI for this page, for reference purposes)
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