Impact of interfacial coupling of oxygen octahedra on ferromagnetic order in La_0.7Sr_0.3MnO₃/SrTiO₃ heterostructures.

ABSTRACT: La_0.7Sr_0.3MnO₃, a half-metallic ferromagnet with full spin polarization, is generally used as a standard spin injector in heterostructures. However, the magnetism of La_0.7Sr_0.3MnO₃ is strongly modified near interfaces, which was addressed as "dead-layer" phenomenon whose origin is still controversial. Here, both magnetic and structural properties of La_0.7Sr_0.3MnO₃/SrTiO₃ heterostructures were investigated, with emphasis on the quantitative analysis of oxygen octahedral rotation (OOR) across interfaces using annular-bright-field imaging. OOR was found to be significantly altered near interface for both La_0.7Sr_0.3MnO₃ and SrTiO₃, as linked to the magnetism deterioration. Especially in La_0.7Sr_0.3MnO₃/SrTiO₃ superlattices, the almost complete suppression of OOR in 4 unit-cell-thick La_0.7Sr_0.3MnO₃ results in a canted ferromagnetism. Detailed comparisons between strain and OOR relaxation and especially the observation of an unexpected La_0.7Sr_0.3MnO₃ lattice c expansion near interfaces, prove the relevance of OOR for the magnetic properties. These results indicate the capability of tuning the magnetism by engineering OOR at the atomic scale.

SUBMITTER: Li X 

PROVIDER: S-EPMC5225431 | biostudies-literature | 2017 Jan

REPOSITORIES: biostudies-literature