Maheshwari, P. K. and Reddy, V. Raghavendra and Gahtori, Bhasker and Awana, V. P. S. (2019) Detailed physical property characterization of FeTe1-xSex(0.00 <= x <= 0.50) single crystals. Materials Research Express, 6 (4). 046003- 046013. ISSN 2053-1591

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Abstract

Here, we report self flux single crystal growth of FeTe1-xSex(0.00 <= x <= 0.50) series via solid state reaction route; the resulted crystals as seen are shiny. X-Ray diffraction (XRD) performed on the surface of crystals elucidated the growth in (00l) plane, i.e. orientation in c-direction only. Scanning electron microscopy (SEM) images showed slab like morphology and EDX (Energy dispersive x-ray analyzer) confirmed that the crystals are closed to their designed compositions. Rietveld analysis of the XRD patterns of crushed crystal powders showed that the cell parameters decrease with Se content increase. Coupled magnetic/structural phase transition temperature, seen as a step in resistivity for the lower Se concentration i.e. 0.00 <= x <= 0.07, decreases from around 65 K for x = 0.0 to 50 K for x = 0.07 and it is not detected for higher x values. Superconductivity is observed by resistivity measurement for higher Se concentration i.e. 0.07 <= x <= 0.50, up to a maximum temperature of 14 K at x = 0.50. Thermally Activated Flux Flow (TAFF) analysis based on high field transport measurements in superconducting region done for x = 0.20 crystal exhibited activated flux energy to be decreasing from 12 meV (0.5Tesla) to 4.6 meV (14Tesla). Raman spectroscopy at room temperature of synthesized samples exhibits all the allowed phonon modes with slight shift to higher frequency with Se content. Mossbauer spectra of FeTe1-xSex crystals series were recorded at 300 and 5 K. At 5 K, the average hyperfine field decreases systematically with Se content increase from 10.6 to 6.1Tesla for x = 0.0 to x = 0.20 samples. This indicates a possibility of co-existing magnetism and superconductivity in 0.07 <= x <= 0.20 crystals. For x = 0.50 sample, no hyperfine field related to magnetic ordering is seen. Based on above results, detailed phase diagram of the FeTe1-xSex(0.00 <= x <= 0.50) compounds is defined in the present study.

Item Type:	Article
Additional Information:	Copyright for this article belongs to M/s IOP Publishing.
Subjects:	Materials Science
Divisions:	UNSPECIFIED
Depositing User:	Mr. Yogesh Joshi
Date Deposited:	06 Feb 2020 07:20
Last Modified:	06 Feb 2020 07:20
URI:	http://npl.csircentral.net/id/eprint/4143

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