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 based on polar perovskite KTaO 3 . Their properties vary greatly with the number of ALs ( n AL ) and the stoichiometric ratio. In the few-AL limit ( n AL ≤ 14), the even AL (EL) systems with the chemical formula (KTaO 3 ) n are semiconductors, while the odd AL (OL) systems with the formula K n +1 Ta n O 3 n +1 or K n Ta n +1 O 3 n +2 are half-metal except for the unique KTa 2 O 5 case which is a semiconductor due to the large Peierls distortions. After reaching a certain critical thickness ( n AL > 14), the EL systems show ferromagnetic surface states, while ferromagnetism disappears in the OL systems. These predictions from fundamental complexity of polar perovskite when approaching the two-dimensional (2D) limit may be helpful for interpreting experimental observations later. Density functional theory predictions of polar perovskite KTaO 3 when approaching the two-dimensional (2D) limit for electrically neutral and charged few-atomic-layer cases.