Influence of antisite disorders on the magnetic properties of double perovskite Nd2NiMnO6

• Polycrystalline Nd2NiMnO6 sample was prepared by solid state reaction method.
• Reitveld refinement of Powder XRD pattern suggests the monoclinic symmetry with P21/n space group.
• The reduction in the value of saturation magnetization (~2 μΒ/f.u.) suggests the presence of antisite disorders in the sample.
• The observation of exchange bias (EB) effect in this compound confirms the presence of antiferromagnetic APBs as well as antisite disorders in the sample.
• EB is due to exchange coupling at FM/AFM interface and not due to FM/SG interface as verified by the memory effect measurements.

The structural and magnetic properties of polycrystalline Nd2NiMnO6 (NNMO) synthesized by solid state reaction method have been investigated. Rietveld refinement of Powder X-Ray diffraction data suggests that NNMO compound crystallizes in monoclinic phase with space group P21/n.   Magnetic measurements reveal an additional magnetic transition TC׳~85 K due to to Ni3+–O–Mn3+ antiferromagnetic superexchange interaction along with ferromagnetic transition ~196 K in M–T curve, leading to antiferromagnetic interactions in this compound. High sintering temperature (upto 1100 °C) leads to the formation of antisite disorders and antiferromagnetic antiphase boundaries in the present sample. The magnetic hysteresis measurements show ferromagnetic behavior with low saturation magnetization value (~2 μB/f.u.) than the theoretical spin-only value (5 μB/f.u.) of Ni/Mn ions. Hence, antisite disorders diminish the long range ferromagnetic ordering and also affect the magnetic properties of this compound. Exchange bias behavior has been observed in the hysteresis loops when the sample was field cooled from 300 K to 5 K. Exchange coupling between the ferromagnetic moments and antiferromagnetic antiphase boundaries is responsible for the observation of exchange bias in the present system.