Measurements of trapped magnetic field in single crystal of CaKFe₄As₄ superconductor

CaKFe₄As₄ is a stoichiometric iron-based superconductor with a Tc of ~35 K. [A. Iyo, et al., JACS 138, 3410 (2016).] It can be grown in single crystal form [W. R. Meier, et al, PRB 94, 064501 (2016); PR Mat. 1, 013401 (2017)] with well defined and moderate pinning of vortices [A. Fente, et al., PRB 97, 134501 (2018); N. Haberkorn, et al., PRB 100, 064524 (2019)]. This combination of properties make CaKFe₄As₄ an ideal system for the study of trapped magnetic flux. Inspired by a recent work in high T_c superhydrides under megabar pressures [V. Minkov, et al., arXiv:2206.14108] we performed comprehensive, anisotropic measurements of trapped magnetic field in CaKFe₄As₄ at ambient pressure. We will present the results of the measurements and analysis of obtained superconducting parameters of CaKFe₄As₄ together with a discussion of the advantages of the method and possible artifacts in such measurements.