Combined effects of post-growth thermal treatment and chemical substitution on physical properties of CaFe₂As₂

Hedgehog spin-vortex crystal stabilized in a hole-doped iron-based superconductor

“…The chemical structure of CaKFe 4 As 4 and spin-orbit coupling conspire to stabilize this phase exposing the complex magnetism in FeSCs. This first experimental realization of SVC order in a magnetic superconductor opens a new platform to study multi-component, non-collinear magnetic phases and their interplay with superconductivity.MethodsSingle crystals of Co-and Ni-doped CaKFe 4 As 4 were grown out of a high-temperature solution rich in transition-metals and arsenic similar to the procedure used for the pure compound22,33 .Transition-metal arsenides precursors, M 0.512 As 0.488 (M = Fe, Co, Ni), were synthesized from ground arsenic lumps (Alfa Aesar 99.9999%) and transition-metal powders [Fe (Alfa Aesar 99.9+% metals basis), Co (Alfa Aesar 99.8% metals basis), Ni (Alfa Aesar 99.9% metals basis)] in a rotating fused-silica ampoule in a purpose-built tube furnace as described in Ref 34…”

Studies of spin dynamics in 122 transition metal arsenides using inelastic neutron scattering technique

“…On the other hand, the presence of the strong firstorder magnetostructural transition effectively forbids the coexistence of AFM and SC states in Ca(Fe 1−x Co x ) 2 As 2[84]. In case of tin (Sn) flux grown sample, there are reports of coexistence of SC and the AFM state in Ca(Fe 1−x Co x ) 2 As 2 as well, but, the issue of reproducibility and inhomogeneity in Sn-flux grown samples indicate the possibility of mixed phases[77,85]. Therefore, the AFM and SC could arise from the different parts of the heterogeneous sample.…”

“…2.8is for self-flux (FeAs as a flux) grown sample and it illustrates the absence of the coexistence in Ca(Fe 1−x Co x ) 2 As 2 . In addition, in self-flux grown Ca(Fe 1−x Co x ) 2 As 2 the post growth treatment (annealing/quenching) should be taken into consideration as the annealing and quenching affects the property and phase diagram looks different with annealing temperatures[77,84,85].…”