Thickness dependent interfacial magnetic coupling in [La2NiMnO6/LaMnO3] multilayers

In the present work, interfacial magnetic exchange coupling at FM/AFM interface has been studied by varying the thickness of AFM layer (LaMnO3) in (La2NiMnO6/LaMnO3)15 multilayer thin film based system. In multilayer thin films, the thickness of LMO was varied from 30 to 50 Å, while the thickness of LNMO was kept constant at 100 Å. Thin films of LNMO, LMO and LNMO/LMO multilayers have been deposited by pulsed laser deposition technique on (0 0 1) LaAlO3 substrate. The thin films have been studied for their structural and magnetic properties. XRD analysis reveals the c-axis epitaxial growth of LNMO, LMO and their multilayer thin films. Exchange bias (EB) effect has been observed in the field cooled hysteresis loops of multilayer thin films and the interaction between FM and AFM spins at the interface is responsible for the observed effect. EB measurements reveal that the thickness variation influences the interfacial interaction between two layers. The EB increases with increasing AFM film thickness in multilayer thin film samples and maximum EB (∼740 Oe) is observed for sample with 50 Å thickness of AFM layer. Temperature dependence of EB and training effect measurements have also been performed to confirm the EB in the sample.