Maheshwari, P. K. and Gahtori, Bhasker and Gupta, Anurag and Awana, V. P. S. (2017) Impact of Fe site Co substitution on superconductivity of Fe1-xCoxSe0.5Te0.5 (x=0.0 to 0.10): A flux free single crystal study. AIP Advances, 7 (01500). 015006-1-015006-11. ISSN 2158-3226

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We report synthesis of Co substitution at Fe site in Fe1-xCoxSe0.5Te0.5 (x= 0.0 to 0.10) single crystals via vacuum shield solid state reaction route using flux free method. Single crystal XRD results showed that these crystals grow in (00l) plane i.e., orientation in c-direction. All the crystals possess tetragonal structure having P4/nmm space group. Detailed scanning electron microscopy (SEM) images show that the crystals are grown in slab-like morphology. The EDAX results revealed the final elemental composition to be near stoichiometric. Powder X-Ray diffraction (PXRD) Rietveld analysis results show that (00l) peaks are shifted towards higher angle with increasing Co concentration. Both a and c lattice parameters decrease with increasing Co concentration in Fe1-xCoxSe0.5Te0.5 (x= 0.0 to 0.10) single crystals. Low temperature transport and magnetic measurements show that the superconducting transition temperature (T-c), decreases from around 12K to 10K and 4K for x=0.03 and x=0.05 respectively. For x= 0.10 crystal superconductivity is not observed down to 2K. Electrical resistivity measurement of Fe0.97Co0.03Se0.5Te0.5 single crystal under magnetic field up to 14Tesla for H parallel to ab and H parallel to c clearly showed the anisotropy nature of superconductivity in these crystals. The upper critical field H-c2(0), being calculated using conventional one band Werthamer-Helfand-Hohenberg (WHH) equation, for x=0.03 crystal comes around 70Tesla, 45Tesla and 35Tesla for normal state resistivity criterion rho(n) = 90%, 50% and 10% criterion respectively for H parallel to c and around 100Tesla, 75Tesla and 60Tesla respectively for H parallel to ab. The activation energy of Fe0.97Co0.03Se0.5Te0.5 single crystal is calculated with the help of TAFF model for both H//c andH//ab direction. In conclusion, Cosubstitution at Fe site in Fe1-xCoxSe0.5Te0.5 suppresses superconductivity.

Item Type: Article
Additional Information: Copyright for this article belongs to M/s American Institute of Physics.
Subjects: Materials Science
Applied Physics/Condensed Matter
Nanoscience/ Nanotechnology
Depositing User: Users 27 not found.
Date Deposited: 10 Oct 2018 08:55
Last Modified: 10 Oct 2018 08:55

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