Long‐Range Antiferromagnetic Order on Spin Ladders SrFe2S2O and SrFe2Se2O As Probed by Neutron Diffraction and Mössbauer Spectroscopy

• Published in: European journal of inorganic chemistry Vol. 2017; no. 32; pp. 3829 - 3833
• Main Authors: Guo, Hanjie, Fernández‐Díaz, Maria‐Teresa, Komarek, Alexander Christoph, Huh, Sungjoon, Adler, Peter, Valldor, Martin
• Format: Journal Article
• Language: English
• Published: Weinheim Wiley Subscription Services, Inc 01.09.2017
• Subjects: Antiferromagnetism; Chalcogens; Diffraction; Ferromagnetism; Filing; Inorganic chemistry; Iron; Ladder compounds; Magnetic moments; Magnetic properties; Neutron diffraction; Neutrons; Polarity; Selenium; Strontium compounds; Sulfur
• ISSN: 1434-1948; 1099-0682
• DOI: 10.1002/ejic.201700684

Powder neutron diffraction data on spin ladder compounds SrFe2Ch2O (Ch = S, Se) indicate that their magnetic ground states feature long‐range antiferromagnetic spin ordering with k = [0,0,0]. The superexchange interaction is antiferromagnetic across each rung via oxygen but ferromagnetic along the ladders via Ch. At 10 K, the ordered spins point towards the center of the ladders but are faintly canted away from a collinear state. The sizes of the ordered moments are 3.3 and 3.5 µB Fe–1 for SrFe2S2O and SrFe2Se2O, respectively. The polar, heteroleptic, tetrahedral FeCh3O coordination suggests an angle of 8° between the local structure polarity and the magnetic moment spin orientation. Mössbauer spectroscopic data confirm the magnetic ordering scenario and indicate that the local Fe–O bond rules the electric field gradient at the Fe‐site. SrFe2Ch2O (Ch = S, Se) exhibit long‐range antiferromagnetic ordering on spin ladders. Across the rung, an oxygen ion bridges for antiferromagnetic spin interactions while ferromagnetic interactions dominate along and between ladders via Ch. Mössbauer spectroscopic data suggest that the local electric field gradient at the Fe‐site is dominated by the Fe–O bond in the FeCh3O tetrahedron.