= Mn and Cr) single crystals*

Stoichiometric CaKFe₄As₄ is a Fe-based superconductor which has a critical temperature at 35 K. Substituting Fe with Ni or Co suppresses superconductivity and stabilizes an unusual hedgehog spin-vortex crystal magnetic structure [1]. There is a range of concentrations where superconductivity and magnetism coexist [2,3,4]. Having in mind different effect of [Fe, Co] and [Mn, Cr] substitutions in BaFe₂As₂, we grew single crystals of CaK(Fe_1-xA_x)₄As₄ (A = Cr and Mn) and characterized them by magnetic and transport measurements. Phase diagrams of CaK(Fe_1-xA_x)₄As₄ (A = Fe, Co, Mn, Cr) will be compared and the observed trends will be discussed in the context of Fe-based superconductors.
[1] W. R. Meier, et al., npj Quant. Mat. 3, 5 (2018).
[2] S. L. Bud'ko, et al., arXiv1810.07084v1 (2018).
[3] A. Kreyssig, et al., Phys. Rev. B 97, 224521 (2018).
[4] Q.-P. Ding, et al., Phys. Rev. Lett. 121, 137204 (2018).