Few-layer perovskite ${\mathrm{YMnO}}_3$: A first-principles study

The successful preparation of freestanding oxide perovskites down to the few-layer limit inspires the development of two-dimensional multifunctional materials exhibiting both ferroelectric and ferromagnetic properties. In this study, we performed a comprehensive first-principles investigation on the few-layer perovskite ${\mathrm{YMnO}}_3$. Our findings reveal that its monolayer is an antiferromagnetic semiconductor, while other few layers are ferromagnetic half metals. All of them have an in-plane polarization with moderate energy barrier, although the "polarization" of metallic few layers may be not switchable. The distortion modes of few-layer ${\mathrm{YMnO}}_3$ are different from its orthorhombic bulk counterpart which is paraelectric. The symmetry mode analysis reveals that the monolayer ${\mathrm{YMnO}}_3$ displays proper ferroelectric behavior. We have investigated the polarization and magnetism of few-layer polar oxide perovskites and found that they strongly depend on the number of layers. These results will contribute to our current understanding of the properties of few-layer polar oxide perovskites.