Electric-Field Control of Strong Magnetization and Tunable Multiferroic Order in Highly Strained Multiferroic BiFeO3 Films
Jan-Chi Yang1,2*, Qing He3, Chang-Yang Kuo4, Heng-Jui Liu1, Zhiwei Hu4, Jiunn-Yuan Lin2, Ying-Hao Chu1,5,6
1Department of Materials Science and Engineering, National Chiao Tung University, Hsinchu, Taiwan
2Institute of Physics, National Chiao Tung University, Hsinchu, Taiwan
3Department of Physics, Durham University, Durham, United Kingdom
4Max-Planck Institute for Chemical Physics of Solids, Max-Planck Institute, Dresden, Germany
5Department of Electrophysics, National Chiao Tung University, Hsinchu, Taiwan
6Institute of Physics, Academia Sinica, Taipei, Taiwan
* presenting author:楊展其, email:kjyang1120@gmail.com
The ability to externally control the local ferromagnetism of magnetic materials has caught significant attention in the field of condensed matters – with the potential to impact magnetoelectronics, high-frequency magnetic devices and spintronics. In this work, we demonstrate an approach to induce and control the strong magnetization in a single-phased and highly strained multiferroic thin film via an external electric field.
Multiferroic BiFeO3 has its antiferromagnetism coupled strongly with ferroelectricity above room temperature, thereby sheds the light on additional degrees of freedom to trigger new functionalities. The approach leading to our goal is achieved by taking advantages of intriguing coupling among multiferroic BiFeO3 that exhibits correlated ferroelectricity and antiferromagnetism. Firstly, we use epitaxial strain to stabilize a highly distorted rhombohedral phase to suppress the antiferromagnetic Neel temperature, which effectively reduce the strength of super-exchange interaction in BiFeO3. The followed external electric field modulating the polarizations consequently enhances the Dzyaloshinskii-Moriya interaction in the meta-stable BiFeO3 phase, leading to the enhanced magnetization in the thin film. We further reveal the one-to-one correlation of the ferroelectricity and the enhanced magnetizations, confirming the tunable feature of the electrical writing process. In addition, by using such a highly strained thin film, the realization of multiferroic orders with three single well defined parameters, i.e. a single antiferromagnetic axis parallel to b-axis, a ferromagnetic momentum induced by Dzyaloshinskii-Moriya interaction parallel to a-axis and a ferroelectric polarization parallel to c-axis, is achievable. Our results provide an intriguing route to locally control ferromagnetism in a single-phase material via electric field, and to fulfill the realization of single multiferroic order in multiferroic films, which lead to novel spintronics and advanced applications.

Keywords: complex oxide, multiferroic, electrical control of magnetism, thin film, BiFeO3