An Ising ferrimagnet with layered and chained magnetic sublattices:

Charge Disproportionation and Magnetoresistivity in a Double Perovskite with Alternate Fe4+(d4) and Mn4+(d3) Layers

“…The Mössbauer data of the precursor consist of two sets of sextets, with the isomer shift ( IS ) of 0.17 and 0.40 mm s –1 for the major and minor subspectrum, respectively, which can be assigned as tetrahedral (Fe‐rich) and octahedral (Mn‐rich) sites. The subspectrum weight ratio of approximately 80:20 agrees well with the previous report of partial site mixing in the precursor (87:13) 11. The spectrum of CFMO at room temperature consists of a paramagnetic singlet with IS = –0.021 mm s –1 , which is assigned as a tetravalent iron in an octahedral environment 3,12,13.…”

“…After the first synthesis of Ca 2 FeMnO 5 by Nakahara et al,9 several groups discussed the crystal and magnetic structure of this material 10,11. The most thorough study by Greedan et al10 revealed the Fe‐rich (Mn‐poor) composition of Ca 2 Fe 1.03 Mn 0.962 O 5 ( Pnma space group) with a small level of Mn/Fe mixing in both octahedral and tetrahedral sites.…”

A Layered Double Perovskite Ca₂FeMnO₆ with Unusually High Valence Fe⁴⁺ Obtained by Low-Temperature Topotactic Oxidation

“…The refinement results listed in Table 1 are essentially the same as those reported previously 11,12) . to the values reported in the previous reports 13) . The result thus also The changes in the valence states of both Fe and Mn are also clearly seen in the XAS results.…”

Structure and magnetic properties of Ca2Fe1−xMnxAlO5+δ

“…Rykov and co-workers [23] investigated the Ca 2 FeMnO 5 compound and their results are consistent with the model of an Ising ferrimagnet. In the case of our compounds Ca 2-Fe 1Àx Mn x AlO 5 the presence of the non-magnetic aluminium ions, essentially located in the tetrahedral sites, breaks the coupling between octahedral layers, along the b-axis.…”

“…4 and Table 3). In addition, the fact that in Ca 2 FeAlO 5 the Fe magnetic moments are aligned perpendicularly to the b-axis [13], while in Ca 2 MnAlO 5 [12] and Ca 2 FeMnO 5 [23] the Fe moments are aligned along the b-axis, suggests that magnetic frustration has to be present in the case of our compounds Ca 2 (Fe,Mn)AlO 5 , where all metal ions (Fe, Mn and Al) occupy octahedral sites.…”