Magnetothermodynamics of the Ising antiferromagnet Dy 2 Ge 2 O 7

We report systematic low-temperature measurements of the dc magnetization, ac susceptibility, and heat capacity of dysprosium pyrogermanate $({\text{Dy}}_{2}{\text{Ge}}_{2}{\text{O}}_{7})$ single crystal and powder samples. Our results confirm that ${\text{Dy}}_{2}{\text{Ge}}_{2}{\text{O}}_{7}$ is an anisotropic antiferromagnet. The isothermal field dependent magnetization and the integrated magnetic entropy both indicate that the ${\text{Dy}}^{3+}$ ions behave as Ising-like spins, analogous to those in the pyrochlore spin ice materials. Both single-spin and collective spin-relaxation phenomena appear to lead to spin freezing in this material, again in analogy to observations in the spin ice materials, suggesting that such phenomena may be generic to a broader class of magnetic materials.