CO2 Stress‐Driven Room Temperature Ferromagnetism of Ultrathin 2D Gallium Oxide

Spintronic devices work by manipulating the spin of electrons other than charge transfer, which is of revolutionary significance and can largely reduce energy consumption in the future. Herein, ultrathin two‐dimensional (2D) non‐van der Waals (non‐vdW) γ‐Ga2O3 with room temperature ferromagnetism is successfully obtained by using supercritical CO2 (SC CO2). The stress effect of SC CO2 under different pressures selectively modulates the orientation and strength of covalent bonds, leading to the change of atomic structure including lattice expansion, introduction of O vacancy, and transition of Ga‐O coordination (GaO4 and GaO6). Magnetic measurements show that pristine γ‐Ga2O3 is nonferromagnetic, whereas the SC CO2 treated γ‐Ga2O3 exhibits obvious ferromagnetic behavior with an optimal magnetization of 0.025 emu g−1 and a Curie temperature of 300 K. Ultrathin 2D non‐van der Waals γ‐Ga2O3 with room temperature ferromagnetism is successfully obtained by using supercritical CO2 (SC CO2), which selectively modulates the orientation and strength of covalent bonds in γ‐Ga2O3, leading to the change of atomic structure and magnetic property.