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Effect of interface defects on the magnetoresistance in Bi4Ti3O12/(La, Sr)Mn1−xO3 heterostructures

Huang, Haoliang, Zhai, Xiaofang, Wang, Jianlin, Meng, Dechao, Yun, Yu, Ma, Chao, Zheng, Xusheng, Wu, Lihui, Pan, Haibin, Fu, Zhengping, Lu, Yalin
Journal of materials science 2018 v.53 no.13 pp. 9627-9634
chemical structure, lanthanum, oxides, strontium, transmission electron microscopy
Heterostructure between layered ferroelectric oxide Bi₄Ti₃O₁₂ and perovskite (La, Sr)Mn₁₋ₓO₃ is highly interesting due to the need to explore new types of functional heterostructures. However, fabricating such heterostructures with high quality is challenging because of the non-isostructural crystalline symmetry of the two constituents. In this work, we constructed two different heterostructures, in which the Bi₄Ti₃O₁₂ layers with precisely controlled thicknesses were deposited on insulating La₀.₇Sr₀.₃Mn₀.₈₁O₃ and conducting La₀.₇Sr₀.₃MnO₃ bottom layers, respectively. Results of cross section transmission electron microscopy identified rough interfaces between insulating (La, Sr)Mn₁₋ₓO₃ and Bi₄Ti₃O₁₂, while sharp interfaces between metallic (La, Sr)Mn₁₋ₓO₃ and Bi₄Ti₃O₁₂. In the former, levels of intermixing and charge leaking are strongly dependent on the thickness of the Bi₄Ti₃O₁₂ capping layer, which induces a capping-layer-thickness-dependent magnetoresistance. These results demonstrated that the interfacial defect is a critical factor for designing functional heterostructures composed of layered oxide and perovskite oxide.