The effect of antisite disorder on magnetic and exchange bias properties of Gd-substituted Y₂CoMnO₆double perovskite

Combining experimental investigations and first-principles density functional theory (DFT) calculations, we report physical and magnetic properties of Gd-substituted Y₂CoMnO₆double perovskite, which are strongly influenced by antisite-disorder-driven spin configurations. On Gd doping, Co and Mn ions are present in mixed-valence (Co³⁺, Co²⁺, Mn³⁺and Mn⁴⁺) states. Multiple magnetic transitions have been observed: (i) paramagnetic to ferromagnetic transition is found to occur atT_C= 95.5 K, (ii) antiferromagnetic transition atT_N= 47 K is driven by3d-4fpolarization and antisite disorder present in the sample, (iii) change in magnetization belowT⩽20 K, primarily originating from Gd ordering, as revealed from our DFT calculations. AC susceptibility measurement confirms the absence of any spin-glass or cluster-glass phases in this material. A significantly large exchange bias effect (HEB= 1.07 kOe) is found to occur below 47 K due to interfaces of FM and AFM clusters created by antisite-disorder.