Predicting the structural, electronic and magnetic properties of few atomic-layer polar perovskite

Density functional theory (DFT) calculations are performed to predict the structural, electronic and magnetic properties of electrically neutral or charged few-atomic-layer (AL) oxides whose parent systems based on polar perovskite $KTaO_{3}$. Their vary greatly with number ALs ($n_{AL}$) stoichiometric ratio. In few-AL limit ($n_{AL}\leqslant 14$), even AL (EL) chemical formula $(KTaO_{3})_{n}$ semiconductors, while odd (OL) ($K_{n+1}Ta_{n}O_{3n+1}$ $K_{n}Ta_{n+1}O_{3n+2}$) half-metal except for unique $KTa_{2}O_{5}$ case which is a semiconductor due large Peierls distortions. After reaching certain critical thickness ($n_{AL}>14$), EL show ferromagnetic surface states, ferromagnetism disappears in OL systems. These predictions from fundamental complexity when approaching two-dimensional (2D) may be helpful interpreting experimental observations later.