We report mean-field critical behavior in ${\mathrm{Eu}}_2{\text{MnSi}}_2{\mathrm{O}}_7$, a melilite-type ferrimagnet with spin-only ${\mathrm{Eu}}^{2+}$ and ${\mathrm{Mn}}^{2+}$ moments and negligible orbital contributions. Magnetization measurements combined with neutron powder diffraction reveal critical exponents close to the mean-field values, indicating that long-range dipolar interactions govern the asymptotic critical behavior in this insulating ferrimagnet. The refined magnetic structure, described by the magnetic space group $P{2}_1{2}_1^{\prime }{2}^{\prime }$, exhibits a tilted ferrimagnetic configuration driven by the Dzyaloshinskii-Moriya interaction, reflecting the noncentrosymmetric nature of the lattice. These results extend the applicability of mean-field theory to complex insulating magnets and establish ${\mathrm{Eu}}_2{\text{MnSi}}_2{\mathrm{O}}_7$ as a platform for exploring ferrimagnetism and long-range interactions. To our knowledge, this is the first insulating ferrimagnet in which dipolar interactions drive mean-field criticality.

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• Critical exponents
• Ferrimagnets
• Neutron diffraction