  Clear experimental evidence of re-entrant spin glass state has been revealed
in Er doped CeFe2 compounds. The zero field cooled - field cooled bifurcation
in dc magnetization, frequency dependence of freezing temperature, relaxation
in zero field cooled magnetization and presence of large remanence confirm the
spin glass state in these compounds. Frequency dependence is found to follow
the critical slowing down mechanism. The random substitution of Er and the
change in the valence state of Ce along with an enhancement of the
ferromagnetic component in the Fe sublattice seem to be responsible for the
spin glass state. Using detailed experimental protocols, we also prove that the
low temperature state in these compounds is not a magnetic glass. The absence
of exchange bias gives an indication that there is no coexistence of
ferromagnetism and spin glass state in these compounds. The RSG state is found
to be associated with the randomly magnetized clusters instead of atomic level
randomness.
