A high density CaKFe4As4 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 CaKFe4As4. 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 μΩ 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 ΔTc 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 Jc), 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.
Cite
@article{arxiv.2403.19981,
title = {Synthesis of CaKFe$_4$As$_4$ bulk samples with high critical current density using a spark plasma sintering technique},
author = {Shigeyuki Ishida and S. Pavan Kumar Naik and Yoshinori Tsuchiya and Yasunori Mawatari and Yoshiyuki Yoshida and Akira Iyo and Hiroshi Eisaki and Yoshihisa Kamiya and Kenji Kawashima and Hiraku Ogino},
journal= {arXiv preprint arXiv:2403.19981},
year = {2024}
}