Static magnetic order of Sr$_{4}$A$_{2}$O$_{6}$Fe$_{2}$As$_{2}$ (A = Sc and V) revealed by local probes

TL;DR

This study reveals static magnetic order in Sr4A2O6-xFe2As2 compounds with A = Sc and V using local probes, showing antiferromagnetic order in the non-superconducting phase and coexistence of magnetism and superconductivity in the V-doped phase.

Contribution

It provides the first local-probe evidence of magnetic order in Sr4A2O6-xFe2As2 compounds, highlighting similarities with other FeAs systems.

Findings

Antiferromagnetic order in Sr4Sc2O6Fe2As2 below 35 K.

Coexistence of static V magnetic order and superconductivity in Sr4V2O6.4Fe2As2.

Magnetic behavior of Fe moments aligns with 1111 and 122 FeAs systems.

Abstract

Static magnetic order of quasi two-dimensional FeAs compounds Sr4A2O6-xFe2As2, with A = Sc and V, has been detected by 57Fe Moessbauer and muon spin relaxation ({\mu}SR) spectroscopies. The non-superconducting stoichiometric (x = 0) A = Sc system exhibits a static internal/hyperfine magnetic field both at the 57Fe and {\mu}+ sites, indicating antiferromagnetic order of Fe moments below TN = 35 K with ~ 0.1 Bohr magneton per Fe at T = 2 K. The superconducting and oxygen deficient (x = 0.4) A = V system exhibits a static internal field only at the {\mu}+ site below TN ~ 40 K, indicating static magnetic order of V moments co-existing with superconductivity without freezing of Fe moments. These results suggest that the 42622 FeAs systems belong to the same paradigm with the 1111 and 122 FeAs systems with respect to magnetic behavior of Fe moments.