The effect of antisite disorder on magnetic and exchange bias properties of Gd-substituted Y$_2$CoMnO$_6$ double perovskite

Abstract

Combining experimental investigations and first-principles DFT calculations, we report physical and magnetic properties of Gd doped Y 2 CoMnO 6 (YCMO) double perovskite (DP), which are strongly influenced by antisite-disorder(ASD)-driven spin configurations. On Gd doping, Co and Mn ions are present in mixed valence (Co 3+ , Co 2+ , Mn 3+ and Mn 4+ ) states. Multiple magnetic transitions have been observed: i) field-induced paramagnetic to ferromagnetic transition at T C =95.5 K, ii) antiferromagnetic transition at T N =47 K due to 3d − 4f polarisation, iii) change in magnetization below T ≤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 (EB) effect (H EB =1.07 kOe) is found to occur below 47 K due to interfaces of FM and AFM clusters created by antisite-disorder.