Synthesis of CaKFe${}_4$As${}_4$ bulk samples with high critical current density using a spark plasma sintering technique

Abstract

A high density CaKFe${}_4$As${}_4$ bulk sample was successfully synthesized using a spark plasma sintering (SPS) technique. The density of the synthesized sample was 5.02 g cm${}^{-3}$, corresponding to 96.2% of the theoretical density of CaKFe${}_4$As${}_4$. Moreover, a reasonably high Vickers hardness of 1 GPa was measured. The electrical resistivity of the SPS bulk sample was as low as approximately 600 $\mu \Omega$ cm at 300 K, which is smaller than that of the ordinary sintered polycrystalline sample by nearly one order of magnitude, and exhibited a sharp superconducting transition, with the transition width $\Delta {\text{T}}_c$ less than 2 K, indicating an improved grain connectivity. The critical current density of the SPS bulk sample, as calculated from the magnetization hysteresis loops (magnetic ${\text{J}}_c$), reached 18 kA cm${}^{-2}$ at 4.2 K under 5 T, which is the highest among the iron-based superconductor polycrystalline samples reported thus far.

13 pages, 6 figures, 1 table

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Cited by in corpus (2)

• Effect of impurity phase and high-pressure synthesis on the superconducting properties of CaKFe4As4
• Synthesis of $c$-axis textured CaKFe${}_4$As${}_4$ superconducting bulk via spark plasma texturing technique