Nonstoichiometric Mn-substituted $\mathrm{ErF}{\mathrm{e}}_2$ compounds, historically and hereafter written as $\mathrm{ErF}{\mathrm{e}}_2\mathrm{M}{\mathrm{n}}_x$ ($x=0-0.4$), with the $\mathrm{MgC}{\mathrm{u}}_2$-type cubic Laves-phase structure, magnetically ordered at room temperature, have been probed by ${}^{57}\mathrm{Fe}$ Mössbauer spectroscopy, aiming at the determination of the influence of Mn atoms on the state of iron and clarification of Mn atomic distribution in the lattice. Mössbauer spectra have been processed in the frame of the tensor approach to the description of hyperfine interactions, which allowed determination of the main hyperfine parameters and partition of the isotropic and anisotropic parts of the hyperfine field at Fe nuclei, with its direction being set down. The magnetic moment at Fe atoms at room temperature is estimated to be $1.3{\mu }_{\mathrm{B}}$ for $\mathrm{ErF}{\mathrm{e}}_2$ and it decreases with increasing the Mn content. The magnetic moments of Fe and Mn are ordered ferromagnetically, with Mn atoms having a lower magnetic moment than Fe. The direction of the hyperfine field at ${}^{57}\mathrm{Fe}$ lies in the plane (1-10) and deviates from the [111] axis. The deviation angle increases with increasing Mn concentration. It is shown that the distribution of Mn in the structure of $\mathrm{ErF}{\mathrm{e}}_2\mathrm{M}{\mathrm{n}}_x$ differs from the statistical one, which purports its local ordering. A strong impact of Mn that occupies sites in the rare-earth sublattice on Fe atoms is observed, unlike earlier Mössbauer experiments on quasibinary compounds with the structure of the cubic Laves phase.

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• Doping effects
• Magnetic anisotropy
• Magnetic order
• Magnetic phase transitions
• Magnetism