Realization of exchange bias control with manipulation of interfacial frustration in magnetic complex oxide heterostructures

Rich exchange bias (EB) behaviors were previously observed when ferromagnetic (FM) materials contacted a spin glass, demonstrating magnetic degrees of freedom of the coupling between the glass and FM spins. However, the correlation between the degree of magnetic spin frustration and the strength of the resulting EB is far from being understood. Here, we systematically investigate the dependency of EB on interfacial spin frustration in magnetic complex oxide heterostructures including ${\mathrm{La}}_0.7{\mathrm{Ca}}_0.3\mathrm{Mn}{\mathrm{O}}₃\text{/}\mathrm{CaMn}{\mathrm{O}}₃$ (LCMO/CMO) systems. The experimental analysis revealed that the extent of interfacial spin frustration is determined by the subtle competition between different types of magnetic orders related to the glassy spin behaviors at the interface. Such spin frustration can be manipulated through strain engineering through changes in the Mn ${e}_g$ orbital by alternating the stacking sequence of the heterostructures. A highly tunable EB field with 95% change of strength between the highly and weakly frustrated heterostructures has been achieved. Magnetic depth profiles of the heterostructures provide convincing evidence that a magnetically depressed region always occurs in the LCMO layer at the LCMO/CMO interfaces irrespective of the stacking sequence. Finally, EB is established at the magnetic interface in the LCMO layer.