Optically Driven Ultrafast Magnetic Order Transitions in Two-Dimensional Ferrimagnetic MXenes

Laser-induced switching of spins in materials is of great interest to revolutionize future magnetic storage technology and spintronics, which is generally realized in multicomponent ferrimagnetic (FiM) compounds but rare in 2D magnets. Using density functional theory (DFT) calculations, we show that 2D MXenes, including Cr₂VC₂F₂, Mo₂VC₂F₂, Mo₂VN₂F₂, Mo₃C₂F₂, and Mo₃N₂F₂, have unusual FiM order. Interestingly, our real-time time-dependent DFT simulations demonstrate that laser pulses can directly induce ultrafast spin-selective charge transfer between magnetic sublattices in a few femtoseconds and further generate dramatic changes in the magnetic structure of these MXenes, including a transition from FiM to transient ferromagnetism (FM). The microscopic mechanism behind this ultrafast switching of spin is governed by the optically induced intersite spin transfer (OISTR) effect, which theoretically enables the ultrafast optical manipulation of the magnetic state in MXenes. Our results open new opportunities for exploring the optical manipulation of spin in 2D magnets.