Abstract
We report on the specific heat, magnetization and ac susceptibility measurements of single crystals of hybrid frustrated magnets Gd1.8Tb0.2Ti2O7 and Gd1.5Tb0.5Ti2O7. The analysis of experimental data revealed that, although partial replacing of the Gd3+ ions by the Tb3+ ions in the Gd2Ti2O7 host lattice slightly enhances antiferromagnetic coupling, as inferred from the evolution of the paramagnetic Curie-Weiss temperature, the ordering temperature gradually decreases.
Paramagnetic correlations introduced by the Tb3+ ions cause this perturbation, altering the effective further neighbor interactions and destabilizing the ground state in Gd2Ti2O7. In addition, the low-energy states of Gd2-xTbxTi2O7 are suggested to possess a nature different from those in parent members Tb2Ti2O7 and Gd2Ti2O7.
Finally, the frequency-dependent magnetic susceptibility behavior in Gd1.5Tb0.5Ti2O7 is consistent with the formation of a spin-glass-like state indicating a pronounced slowing down of the dynamical response of the studied hybrid magnets.