Abstract
CaFeGe2O6, the germanium-analogue to the mineral Hedenbergite, has been synthesized at 1273 K in evacuated SiO2-glass-tubes. Powder neutron diffraction data collected between 4 K and 300 K were used to evaluate the magnetic spin as well as the nuclear crystal structure and its T-evolution. CaFeGe2O6 is monoclinic, C2/c, a = 10.1778(5) Å, b = 9.0545(4) Å, c = 5.4319(3) Å, β = 104.263(3)°, Z = 4 at room temperature. No change of symmetry was observed down to 4 K. Below 43 K, additional magnetic Bragg reflections appear, which can be indexed on the basis of a commensurate magnetic propagation vector k [1, 0, 0]. The successful description of the magnetic spin structure reveals a ferromagnetic spin coupling within the Fe2+O6 M1 chains, while the coupling between the chains is antiferromagnetic. Spins are oriented collinearly within the a–c plane and form an angle of ∼60° with the crystallographic a-axis. The magnetic moment at 4 K amounts to about 4.4 μB. The observed magnetic structure is similar to that of other Ca-clinopyroxenes. The present data are put into context with the structural and magnetic properties of other pyroxenes – among them magnetoelectric and multiferroic pyroxene-type compounds.
© by Oldenbourg Wissenschaftsverlag, München, Germany
