Coexistence of Exchange Spring and Exchange Bias Effect in SrFeO_2.5/LaCoO₃ Heterostructures

Abstract

Strain-sensitive LaCoO₃ was epitaxially employed as the ferromagnetic layer, while SrFeO_2.5 was used as the antiferromagnetic layer to fabricate SrFeO_2.5/LaCoO₃ bilayers. When the LaCoO₃ layer is relatively thin, the bilayers exhibit an exchange spring behavior akin to soft/hard magnetic coupling. However, when the LaCoO₃ layer transitions from being thin to thick, the bilayers transform into a single ferromagnetic-phase magnetization reversal mode. Meanwhile, all the bilayers are accompanied by an obvious exchange bias effect. Extensive experimental results indicate that the changes in the magnetization reversal process and the appearance of exchange bias effect are closely associated with the pinning effect caused by magnetic coupling interaction at the ferromagnetic/antiferromagnetic interface, rather than the soft/hard magnetic phases generated by the LCO layer induced by the substrate.

Keywords

epitaxial strain / SrFeO_2.5/LaCoO₃ bilayer / exchange bias / exchange spring

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