| AVS 61st International Symposium & Exhibition | |
| Magnetic Interfaces and Nanostructures | Tuesday Sessions |
| Session MI+MG-TuA |
| Session: | Development of Multiferroic Materials (2:20- 5:00PM) MIND Panel Discussion (5:00-6:30 pm) |
| Presenter: | Weida Wu, Rutgers University |
| Authors: | Y. Geng, Rutgers University X.-Y. Wang, Rutgers University S.-W. Cheong, Rutgers University W. Wu, Rutgers University |
| Correspondent: | Click to Email |
Multiferroics are materials with coexisting magnetic and ferroelectric orders, where inversion symmetry is also broken [1-5]. The cross-coupling between two ferroic orders can result in strong magnetoelectric coupling. Therefore, it is of both fundamental and technological interest to visualize cross-coupled topological defects in multiferroics. Indeed, topological defects with six interlocked structural antiphase and ferroelectric domains merging into a vortex core were revealed in multiferroic hexagonal manganites [6, 7]. Numerous Z6 vortices are found to form an intriguing self-organized network, and may be used to test Kibble-Zurek model of early universe [8, 9]. Many emergent phenomena, such as enhanced conduction and unusual piezoelectric response, were observed in charged ferroelectric domain walls protected by these topological defects [10, 11]. In particular, alternating uncompensated magnetic moments were discovered at coupled structural antiphase and ferroelectric domain walls in hexagonal manganites using cryogenic magnetic force microscopy (MFM) [12], which demonstrates the coupling between ferroelectric and spin orders (B2 phase). The appearance of correlated net moments at the coupled domain walls is in excellent agreement with a phenomenological Landau theory [13], suggesting that the 120° antiferromagnetic order (B2 phase) rotates 4pi in each Z6 vortex. This is further corroborated by the magnetic field dependence of domain wall moments.
*This work is supported by NSF grant # DMR-0844807.
Reference
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