Trapped flux in a tiny crystal of CaKFe₄As₄ at ambient pressure and in a diamond pressure cell

In an extension of our previous work, [1] the measurements of temperature dependent magnetization associated with trapped magnetic flux in a small single crystal of CaKFe4As4, using zero - field - cooled and field - cooled protocols were performed on the same small crystal at ambient pressure without a pressure cell and at 2.2 GPa in a commercial diamond anvil cell, showing comparable results. The data show that with a proper care trapped flux measurements in superconductors indeed could be performed on the samples in DAC under pressure, as was done on superhydrides. [2] Emphasis will be placed on trying to review the experimental concerns, and realities, that are often overlooked or not fully grasped by increasingly common non-experimental papers and preprints. [3,4]

[1] Sergey L. Bud’ko et al., Supercond. Sci. Technol. 36 115001 (2023).

[2] V. S. Minkov et al., Nat. Phys. 19 1293–1300 (2023).

[3] J. E. Hirsch and F. Marsiglio, J. Supercond. Nov. Magn. 35, 3141 (2022).

[4] N. Zen, arXiv:2310.06869v1 (2023).