Improvements of high-field pinning properties of polycrystalline Fe(Se,Te) material by heat treatments


We present the fabrication of FeSe0.5Te0.5 polycrystalline samples by self-flux method, showing the presence of the peak-effect in the vortex lattice configuration. To improve the performances at high magnetic fields for this iron-based superconductor of the 11-family, the two-step solid-state reaction process has been successfully modified by increasing the temperature of the heat treatment and by slowing down the cooling rate. The magnetic field-temperature phase diagram has been investigated by magneto-resistance, magnetization, and heat capacity measurements in applied magnetic fields up to 18 T. The magnetization curves exhibit an enhancement of the peak-effect whose position shifts by varying the temperature, following a similar dependence than that previously reported in high-temperature superconducting materials such as YBa2Cu3O7-δ. The presence of the peak-effect can be correlated to the sample manufacture, since by tuning a proper heat treatment it becomes observable ever more in the magnetic field-temperature phase diagram. This fabrication route paves the way to a systematic increase in the critical current density thus becoming relevant for applications.

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This work was supported by the PON Research and Competitiveness 2007-2013 under Grants PON Nafassy—PONa3_00007.

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Correspondence to G. Grimaldi.

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Fiamozzi Zignani, C., De Marzi, G., Corato, V. et al. Improvements of high-field pinning properties of polycrystalline Fe(Se,Te) material by heat treatments. J Mater Sci 54, 5092–5100 (2019).

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