The recent realization that the rare-earth melilites ${\mathrm{RE}}_2{\mathrm{Be}}_2{\mathrm{GeO}}_7$ host the Shastry-Sutherland lattice within planes of ${\mathrm{RE}}^{3+}$ ions has sparked a number of studies. This family of materials lacks appreciable site mixing and conductivity, making them promising candidates for the Shastry-Sutherland model. Herein, we present the magnetic ground states of two of these rare-earth melilites: RE = Gd and Dy. We find, through measurements of magnetic susceptibility, magnetization, and specific heat capacity (RE = Dy only), that these two melilites are antiferromagnets ($T_N \approx 1$ K). ${\mathrm{Gd}}_2{\mathrm{Be}}_2{\mathrm{GeO}}_7$, in accordance with its electronic configuration, has isotropic single-ion anisotropy but shows a quadratic contribution to its magnetization. ${\mathrm{Dy}}_2{\mathrm{Be}}_2{\mathrm{GeO}}_7$ has Ising-like single-ion anisotropy and is likely an effective spin-$1/2$ system. Both materials exhibit metamagnetic transitions. We identify this transition in ${\mathrm{Dy}}_2{\mathrm{Be}}_2{\mathrm{GeO}}_7$, occurring at 86(1) mT for $T=500$ mK, to likely be a spin-flip transition.

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• Antiferromagnetism
• Dipolar interaction
• Frustrated magnetism
• Magnetic anisotropy