Synthesis and Characterization of Frustrated Spin Ladders SrFe₂S₂O and SrFe₂Se₂O

Abstract

Abstract Chemical pressure was introduced by replacing Ba atoms with Sr atoms in the spin‐ladder compounds AEFe 2 Ch 2 O (AE = Ba, Sr; Ch = S, Se). Powders and small single crystals of SrFe 2 S 2 O and SrFe 2 Se 2 O were synthesized from SrO, Fe, and Ch (S, Se). X‐ray diffraction data were used to determine the crystal structures, which showed prominent magnetic ladderlike sublattices. The Mössbauer spectra of SrFe 2 S 2 O and SrFe 2 Se 2 O suggest the presence of localized divalent Fe ions in the FeCh 3 O structural units (distorted e 3 t 2 3 configuration, S = 2). Single sharp hyperfine patterns at 5 K indicate the formation of simple antiferromagnetic ground states. The spin‐ordering transitions ( T N ) were determined by magnetic, resistivity, and specific heat data to be 216 and 228 K for SrFe 2 S 2 O and SrFe 2 Se 2 O, respectively. At ca. 540 K, both compounds exhibit a similar broad maximum in χ ( Tχ max ). In comparison with BaFe 2 S 2 O and BaFe 2 Se 2 O, the Sr homologues have higher T χ max values, which suggest stronger intersite exchange interactions in accordance with the chemical pressure from the replacement of Sr atoms with Ba atoms. However, the lower Néel temperatures for the Sr homologues supports the idea that magnetic frustration is present, and it clearly has to be considered for this group of compounds.