Exchange Bias Effect in Epitaxial LaMnO3+delta Film Induced by Electron Beam Irradiation

摘要

Phase separation in the perovskite manganites of R(1-)(x)A(x)MnO(3) (R = trivalent lanthanide cation and A = divalent alkaline-earth cation) can induce novel phenomena associated with the interfacial interactions. Here, the occurrence of phase separation and unexpected exchange bias induced by electron beam irradiation (EBI) in the epitaxial LaMnO3+delta (LMO) thin films is reported. The transformation from Mn4+ ion to Mn3+ ion originating from the electron's reducibility, enhances the Mn3+-Mn3+ antiferromagnetic superexchange interaction, resulting in phase separation, namely, the coexistence of ferromagnetic matrix and antiferromagnetic clusters. The formation of the antiferromagnetic phase in the LMO film is closely related to the increase of the out-of-plane lattice constant and the decrease of Curie temperature after EBI. The unexpected exchange bias effect results from the interfacial interaction between the ferromagnetic matrix and antiferromagnetic clusters, triggered by EBI in LMO film. The discovery of exchange bias induced by EBI shed promising light on achieving the tunable exchange bias effect in spintronic devices for single-phase films.