Tuneable Vertical Hysteresis Loop Shift in Exchange Coupled La0.67Sr0.33MnO3-SrRuO3 Bilayer

Harnessing extra degrees of freedom at the heterostructure interface is of crucial importance to bring additional functionalities in modern spintronic devices. Here, a vertical hysteresis loop shift (vertical bias) is demonstrated in an exchange biased system of ferromagnetic thin film heterostructure of La_0.67Sr_0.33MnO₃ (10 nm)-SrRuO₃ (SRO) (20 nm), after field cooling with ±1 T below 100 K close to the Curie temperature (T_C) ≈125 K of SRO and loop sweeping under ±1 T field. Besides, a positive exchange bias (H_EB) is also observed below T_C ≈125 K showing a maximum ≈11 mT at 2 K. The vertical shift is modeled closely using micromagnetic simulations and the layers’ thickness dependency is demonstrated. The reason for the shift is attributed to the simultaneous role of the interfacial antiferromagnetic interaction and the hard anisotropy of SRO against the Zeeman energy. Finally, from the experimental and simulation results, a generalized model of controllable and tunable vertical shift is proposed applicable for other material systems possessing glassy phases, uncompensated/canted spins, absent interfacial exchange coupling, etc., and hence can be informative for the use of vertical shift in future spintronic devices.