Dipolar-driven mean-field criticality in the ferrimagnet Eu${}_2$MnSi${}_2$O${}_7$

Abstract

We report mean-field critical behavior in Eu${}_2$MnSi${}_2$O${}_7$, a melilite-type ferrimagnet with spin-only Eu${}^{2+}$ and 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 Eu${}_2$MnSi${}_2$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.

8 pages, 4 figures

References in corpus (2)

• Magnetic structure of the noncentrosymmetric magnet Sr2MnSi2O7 through irreducible representation and magnetic space group analyses
• Magnetic excitations in the noncentrosymmetric magnet Sr2MnSi2O7