UC Davis

A wedge bilayer of epitaxial 4-8 nm La0.7Sr0.3CoO3(LSCO)/6-nm La0.7Sr0.3MnO3(LSMO), hard and soft ferromagnets (FM) respectively, was studied using soft x-ray magnetic spectroscopy to elucidate the interplay between the magnetic and electronic properties of the constituent layers. This system exhibits magnetic and electronic segregation within the LSCO layer characterized by soft FM Co2+ ions at the interface (s-LSCO), which is biased by the underlying hard LSCO layer (h-LSCO), characterized by predominantly Co3+/Co4+ FM ions. For a 5.1-nm layer, the interfacial Co2+ ion concentration is maximized and the h-LSCO coercivity is minimized, while the opposite is true for a 7.8-nm LSCO layer. These dual trends in Co2+ ion concentration and h-LSCO coercivity within the LSCO serve to independently affect the exchange bias and coercivity of the soft FM layer, resulting in inverse trends between these properties that typically vary simultaneously.