Interfacial reconstruction, exchange bias and photocurrent effect in epitaxial Fe3O4/Co3O4 spinel heterostructure

Abstract Fully spinel epitaxial Fe 3 O 4 /Co 3 O 4 heterostructures were fabricated on the MgAl 2 O 4 substrates by reactive magnetron sputtering, and the interfacial structure, magnetic and optical-electric properties were investigated. An interfacial Co x Fe 3- x O 4 layer with a thickness of ~7 nm is formed between the Fe 3 O 4 and Co 3 O 4 layers through the interdiffusion. The interfacial Co x Fe 3- x O 4 enhances the coercivity of the Fe 3 O 4 /Co 3 O 4 heterostructures. The interfacial coupling between the ferromagnetic Co x Fe 3- x O 4 and the antiferromagnetic Co 3 O 4 also induces large exchange bias due to pinning effect. In addition, based on the strong optical absorption of the Co 3 O 4 layer, the enhanced current (~79%) is achieved in the Fe 3 O 4 /Co 3 O 4 heterostructures under irradiation of the 405-nm laser. Our work helps to understand the interfacial diffusion of the heterostructures, and reveals that the Fe 3 O 4 /Co 3 O 4 heterostructures can be used in optical, electrical and magnetic multifunctional devices.