Investigation of glassy magnetic state in Co doped Eu_0.5 Sr_0.5 MnO₃

Ground state magnetic properties of Eu_0.5 Sr_0.5 Mn_1−x Co_xO₃ (x = 0, 0.02, 0.05, and 0.1) with perovskite structure were investigated through dc magnetization and ac susceptibility measurements. Smaller ionic radii of Eu⁺³ ion makes the ground state magnetic properties of these compounds more interesting. The samples show magnetic memory, large relaxation, frequency-dependent ac susceptibility and aging effects at low temperature, which indicate glassy magnetic ground state in the studied samples. A gradual transition from the spin-glass like ground state to cluster-glass state is also observed with increasing Co concentration. This observation is due to the decrease in double exchange interaction between Mn³⁺ and Mn⁴⁺ ion and hence the ferromagnetic interaction with Co doping. - Highlights: • Large magnetic relaxation confirms evolution through the landscape of energy states. • Clear shift observed in the ac susceptibility confirms glassy magnetic ground state. • Presence of ZFC memory confirms the spin-glass nature of the samples. • Spin-glass to cluster-glass transformation observed with increasing Co concentration.