High temperature spin-freezing transition in pyrochlore Eu2Ti2O7: A new observation from ac-susceptibility

The magnetization (both dc and ac) of pyrochlore Eu2Ti2O7 have been investigated. Ac susceptibility (χ/ & χ//) measurements reveal a new unusual spin freezing below 35 K for pure Eu2Ti2O7. Frequency dependence of these ac χ// peak positions indicate slow spin relaxation near this temperature and it follows the Arrhenius formula suggesting a thermally activated relaxation process. The origin of this spin freezing has been attributed essentially to a single ion process which is associated to Eu3+ spin relaxation. Non-magnetic dilution by Y3+ ions also confirms the single ion freezing.