Electrical control of ferromagnetism in multiferroic bismuth ferrite-based heterostructures

• Main Author: You, Lu
• Other Authors: Yao Kui
• Format: Theses and Dissertations
• Language: English
• Published: 2011
• Subjects: DRNTU::Engineering::Materials::Magnetic materials; DRNTU::Engineering::Materials::Microelectronics and semiconductor materials::Thin films
• Online Access: https://hdl.handle.net/10356/44636
• Institution: Nanyang Technological University

Recent renaissance of magnetoelectric multiferroics pivots on the coupling mechanisms between electrical and magnetic order parameters, as the magnetoelectric coupling might lead to the electrical manipulation of the ferromagnetic spins which is essential to the next generation of spin-based non-volatile memories with low power consumption. BiFeO3 (BFO), as the only known room temperature multiferroic with vigorous magnetoelectric coupling, inspires a potential route to accomplish the functionality of electrically-controllable ferromagnetism through the interface exchange coupling with another ferromagnetic thin layer, which forms the backbone of this dissertation. In the course towards this ultimate goal, the growth kinetics of BFO thin film was firstly investigated to map out the proper growth window. A thorough study of the oxygen pressure dependence reveals a great impact of composition stoichiometry on the relevant ferroelectric properties, which can be elucidated by the interactions between polar order and defect chemistry. Subsequently, the optimization and engineering of the BFO domain structures can be achieved by a number of approaches including compositional yields, film growth rate, vicinal substrates and anisotropic substrates. The domain structures of the as-grown films can be delicately controlled by electric field using quasi-planar electrodes. Quantitative study and domain dynamics of polarization switching under planar geometry create the basis of device architecture for further study.