Oxalate-mediated long-range antiferromagnetism order in Fe2(C2O4)3·4H2O

Abstract

In this paper we reveal for the first time the magnetic properties of iron oxalate tetrahydrate, a compound commercialized for decades but whose structure was solved only recently. Susceptibility measurements and neutron powder diffraction experiments reveal the establishment of a long-range magnetic order below 25 K. The magnetic structure can be described with a propagation vector k = (½, ½, 0). The magnetic ordered phase is characterized by collinear antiferromagnetic couplings between adjacent Fe³⁺ atoms, whatever the chelating mode of the oxalate ligand. Moreover, an analysis of the topology reveals that a fourth Fe–Fe magnetic coupling has to be taken into account to generate 3D long range order.