Magnetic structures of FeGeAs and FeGeP intermetallic compounds: a neutron diffraction and Fe Mössbauer spectroscopy study

• Published in: Dalton transactions : an international journal of inorganic chemistry 2021-02, Vol.5 (6), p.221-222
• Main Authors: Khalaniya, R A, Sobolev, A V, Verchenko, V Yu, Tsirlin, A A, Senyshyn, A, Damay, F, Presniakov, I A, Shevelkov, A V
• Format: Article
• ISSN: 1477-9226; 1477-9234
• DOI: 10.1039/d0dt03923c

Fe 32+ δ Ge 33 As 2 and Fe 32+ δ ′ Ge 35− x P x are quasi-binary intermetallic compounds that possess a rare variant of intergrowth-type crystal structure, which is a combination of the column shaped Co 2 Al 5 and MgFe 6 Ge 6 structure type blocks. The compounds are antiferromagnets with the Néel temperatures around 125 K. Neutron powder diffraction experiments on the samples with δ 0.1, δ ′ 0.5 and x 3 reveal commensurate magnetic ordering of low symmetry in both compounds and a non-monotonic change in the intensities of magnetic reflections. On the other hand, temperature dependence of the hyperfine fields obtained from 57 Fe Mössbauer spectroscopy indicates a gradual, monotonic increase in local magnetic fields upon cooling. We interpret these results as a spin reorientation within the Co 2 Al 5 -type block of the crystal structure, with the possible formation of a non-collinear magnetic order at low temperatures. Between the compounds, the reorientation occurs at significantly different temperatures, however the resulting magnetic structures themselves are similar as well as the average values of the magnetic moments and the hyperfine fields. Fe 32.1 Ge 33 As 2 and Fe 32.5 Ge 32 P 3 demonstrate complex commensurate antiferromagnetic ordering below 125 K accompanied by a spin reorientation upon further cooling.