Interface-Induced Ferroelectric Domains And Charged Domain Walls In Bifeo3/Srtio3 Superlattices

Heterostructures comprising of polar and nonpolar perovskites, such as LaAlO3/SrTiO3, have been extensively studied because of the discovery of a two-dimensional electron (or hole) gas [2DEG (or 2DHG)] at the interface. BiFeO3/SrTiO3 is chemically similar to LaAlO3/SrTiO3 with polar/nonpolar interfaces. However, BiFeO3 exhibits spontaneous ferroelectric polarization, which leads to interesting effects in BiFeO3/SrTiO3. Our theoretical simulations exhibit some different physical phenomena in this system, including interface-induced ferroelectric domains, monodirectional polarization, and 2DEGs (or 2DHGs) at the domain walls. Furthermore, it was identified that the observed 2DEGs (or 2DHGs) were spin polarized and exhibited ferromagnetism. The origin of the ferromagnetic 2DEGs (or 2DHGs) is discussed. These spin-polarized 2DEGs (or 2DHGs) observed in our BiFeO3/SrTiO3 model would be important for fundamental research and applications.