Electric-Field Control of Magnetization in (La,Sr)MnO₃/BiFeO₃ Heterostructures

Wang Junling, Associate Professor

School of Materials Science and Engineering

Nanyang Technological University, Singapore

e-mail: jlwang@ntu.edu.sg

It has been demonstrated experimentally that the magnetic plane and ferroelectric polarization in BiFeO₃ thin films are intimately coupled to each other. ¹ When the spontaneous polarization is rotated by 71° or 109°, the magnetic plane remains perpendicular to the polarization and rotates with it. Similar result was also reported for single-crystalline BiFeO₃, where the spin rotation plane can be toggled by polarization switching. ² These earlier studies lay the foundation for the application of BiFeO₃ in spintronic devices. However, since BiFeO₃ is antiferromagnetic, its direct application in devices is limited. An alternative approach has been proposed, where the change in the antiferromagnetic order of BiFeO₃ is revealed by another ferromagnetic layer on top through exchange coupling between them. ³

We have observed a strong exchange coupling between epitaxial (La,Sr)MnO₃ and BiFeO₃ thin films prepared by pulsed laser deposition. By using piezoelectric force microscopy (PFM) and magnetic force microscopy (MFM), we have studied the ferroelectric domains in BiFeO₃ and magnetic domains in (La,Sr)MnO₃, and confirmed the direct correlation between them. By controlling the growth parameters, BiFeO₃ films with 71° and 109° stripe domains can be obtained, which induce an uniaxial anisotropy in the magnetic properties of (La,Sr)MnO₃ on top. ⁴ Our preliminary test has shown that the magnetic domains in (La,Sr)MnO₃ can be changed upon rotating the ferroelectric domains in BiFeO₃ by an electric field.

References:

1, T. Zhao, A. Scholl, F. Zavaliche et al., Nat. Mater. 5, 823 (2006)

2, D. Lebeugle, D. Colson, A. Forget et al., Phys. Rev. Lett. 100, 227602 (2008)

3, C. Binek and B. Doudin, J. Phys.: Condens. Matter 17, L39 (2005)

4, Lu You, Chengliang Lu, Pan Yang, Guchang Han, Tom Wu, Ulrike Luders, Wilfrid Prellier, Kui Yao, Lang Chen, and Junling Wang, Adv. Mater., 22, 4964 (2010)

Bio：王峻岭博士，1999年本科毕业于南京大学材料科学与工程系，2005年于美国马里兰大学材料科学与工程系获博士学位。 2005-2006在宾夕法尼亚州立大学从事博士后研究，自2006年起，于新加坡南洋理工大学材料科学与工程学院历任助理教授、副教授。共发表 学术论文40余篇，被引3100余次。其中2003年在Science上发表的关于BiFeO3的多铁性论文，被引1500余次，揭开了多铁 性研究热潮的序幕。