Effect of interface defects on the magnetoresistance in Bi4Ti3O12/(La, Sr)Mn1−xO3 heterostructures
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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.
The authors acknowledge the RBS help from Prof. Donglai Feng and Dr. Rui Peng in Fudan University. This work was supported by the National Science Foundation of China (Grant Nos. 11504358 and 11574287), the National Natural Science Foundation of China (51627901), the National Key R&D Program of China (2016YFA0401004), the National Key R&D Program of China (2017YFA0402900) and the Hefei Science Center CAS (2015HSC-SRG052). The authors thank beamline BL08U1A and BL14 B1 of SSRF for providing the beam time.
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Conflict of interest
The authors declare that they have no conflict of interest.
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