Vortex ferroelectric domains, large-loop weak ferromagnetic domains, and their decoupling in hexagonal (Lu, Sc)FeO3

The direct domain coupling of spontaneous ferroelectric polarization and net magnetic moment can result in giant magnetoelectric (ME) coupling, which is essential to achieve mutual control and practical applications of multiferroics. Recently, the possible bulk domain coupling, the mutual control of ferroelectricity (FE) and weak ferromagnetism (WFM) have been theoretically predicted in hexagonal LuFeO 3 . Here, we report the first successful growth of highly-cleavable Sc-stabilized hexagonal Lu 0.6 Sc 0.4 FeO 3 ( h -LSFO) single crystals, as well as the first visualization of their intrinsic cloverleaf pattern of vortex FE domains and large-loop WFM domains. The vortex FE domains are on the order of 0.1–1 μm in size. On the other hand, the loop WFM domains are ~100 μm in size, and there exists no interlocking of FE and WFM domain walls. These strongly manifest the decoupling between FE and WFM in h -LSFO. The domain decoupling can be explained as the consequence of the structure-mediated coupling between polarization and dominant in-plane antiferromagnetic spins according to the theoretical prediction, which reveals intriguing interplays between FE, WFM, and antiferromagnetic orders in h -LSFO. Our results also indicate that the magnetic topological charge tends to be identical to the structural topological charge. This could provide new insights into the induction of direct coupling between magnetism and ferroelectricity mediated by structural distortions, which will be useful for the future applications of multiferroics. Multiferroics: decoupled domains Experiments reveal the decoupling between vortex ferroelectric domains and loop weak ferromagnetic domains in hexagonal Lu 0.6 Sc 0.4 FeO 3 . A team led by Sang-Wook Cheong from the Rutgers University in the USA grows cleavable Sc-stabilized hexagonal Lu 0.6 Sc 0.4 FeO 3 ( h -LSFO) single crystals and visualize cloverleaf patterns of vortex ferroelectric (FE) domains and large-loop weak ferromagnetic (WFM) domains. The WFM domains are much larger in size than FE domains. The distinct sizes and shapes demonstrate the decoupling between ferroelectricity and out-of-plane weak ferromagnetism, which is consistent with a former prediction on the absence of coupled magnetoelectric effects in h -LSFO. Furthermore, they indicate that the magnetic topological charge tends to be identical with the structural topological charge. The results provide insights into coupling between magnetism and ferroelectricity mediat