Superconductivity and magnetism in CaK(Fe1-xMnx)4As4 system*

Substitution of Fe with Ni or Co in CaKFe4As4 suppresses superconductivity and stabilizes an unusual hedgehog spin-vortex crystal magnetic structure [1-4]. Similarly, as Mn is substituted in CaKFe4As4, superconductivity is suppressed and magnetic order appears. Given that it was not possible to induce superconductivity in Ba(Fe1-xMnx)2As2, we can  now study the CaK(Fe1-xMnx)4As4 system so as to gain insight into how the often more local moment like Mn affects superconductivity in these Fe-based superconducting systems. The T-x phase diagram of CaK(Fe1-xMnx)4As4 determined by resistance, magnetization and heat capacity will be presented and compared with the Ni or Co substituted systems. The superconducting critical field data as well as BNC scaling [5] will be also discussed. In addition Pressure-temperature phase diagram determined by resistance under hydrostatic pressure up to 5.15 GPa will also be presented and discussed.