Static magnetic order of Sr4A2O6Fe2As2 (A = Sc and V) revealed by Mössbauer and muon spin relaxation spectroscopies

Static magnetic order of quasi-two-dimensional FeAs compounds Sr4A2O6-xFe2As2, with A= Sc and V, has been detected by Fe57 Mössbauer and muon spin relaxation (μSR) spectroscopies. The nonsuperconducting stoichiometric (x=0) A= Sc system exhibits a static internal/hyperfine magnetic field both at the Fe57 and μ+ 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 μ+ site below TN~40 K, indicating static magnetic order of V moments coexisting 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.