Tuning the interactions in the spin-ice materials Dy2Ge2−xSixO7 by silicon substitution

We report that the lattice constant of Dy_2e_{2-x}i_x_7(x=0, 0.02, 0.08, 0.125 can be systematically reduced by substituting the non-magnetic germanium ion in the cubic pyrochlore oxide with silicon. A multi-anvil high-pressure synthesis was performed up to 16 GPa and 1100 ^\circ to obtain polycrystalline samples in a solid-state reaction. Measurements of magnetization, ac susceptibility, and heat capacity reveal the typical...