CO 2 -Induced Exposure of the Intrinsic Magnetic Surface of BaTiO 3 to Give Room-Temperature Ferromagnetism.

Preparation of low-dimensional ferromagnetic nanomaterials and investigation of their magnetic origin is critical to the exploration of novel materials with various applications such as data storage. Herein, non-van der Waals (non-vdW) BaTiO 3 was successfully stripped to a low-dimensional structure by treating the materials with supercritical CO 2 (SC CO 2 ). Under different CO 2 pressures, SC CO 2 selectively cleaves the covalent bonds of the bulk BaTiO 3 , leading to the exposure of various surfaces. After SC CO 2 treatments, the BaTiO 3 exhibits room-temperature ferromagnetism, which is significantly stronger than conventional treatments. According to the experimental and theoretical investigations, the enhanced ferromagnetic property is attributed to the exposure of the intrinsic surfaces of BaTiO 3 .