Dilution effects in Ho2-xYxSn2O7: From the spin ice to the single-ion magnet

A study of the modifications of the magnetic properties of Ho2-YxSn2O7 upon varying the concentration of diamagnetic Y3+ ions is presented. Magnetization and specific heat measurements show that the Spin Ice ground-state is only weakly affected by doping for x ≤ 0.3, even if non-negligible changes in the crystal field at Ho3+ occur. In this low doping range μSR relaxation measurements evidence a modification in the low-temperature dynamics with respect to the one observed in the pure Spin Ice. For x → 2, or at high temperature, the dynamics involve fluctuations among Ho3+ crystal field levels which give rise to a characteristic peak in 119Sn nuclear spin-lattice relaxation rate. In this doping limit also the changes in Ho3+ magnetic moment suggest a variation of the crystal field parameters.