Stacking-engineered 2D CrSeBr multiferroic for promising quantum information processing applications.

The realization of two-dimensional (2D) multiferroic materials offers promising opportunities for multifunctional electronic device design, especially in enabling the miniaturization and integration of nanodevices. In this work, we present a comprehensive first-principles study of CrSeBr, as a model system that integrates magnetic, ferroelectric, and ferrovalley functionalities. The monolayer CrSeBr exhibits spontaneous valley polarization of up to 26 meV that can be effectively controlled by reversing its magnetization. In the bilayer, these coupled properties can be further manipulated by interlayer sliding. The AA' stacking bilayer possesses an antiferromagnetic (AFM) ground state with band degeneracy at the conduction band minimum and valence band extrema near the K and K' valleys. Sliding from AA' to AB' (AC') stacking induces a magnetic phase transition from AFM to ferromagnetic order, while the further transition from AB' to AC' reverses both the ferroelectric and valley polarizations. By choosing a particular pathway, they demonstrate reduced interlayer sliding energy barriers 12.5 meV f.u.-1for ferroelectric switching, outperforming several existing 2D sliding ferroelectric materials. This highly tunable multiferroicity, enabled by controlling the interlayer stacking order via sliding, provides practical design principles for advanced multifunctional devices. Our findings underscore the vital role of low-dimensional multiferroics in van der Waals structures and pave the way for next-generation electronic, and valleytronic for quantum information processing applications.