Controllable properties and versatile dynamics of meron topological magnetism in van der Waals multiferroic CuCrPS.

The ability to efficiently control topological magnetism is crucial for advancing technological applications and deepening our understanding of magnetic systems. Although emerging van der Waals (vdW) multiferroics present a promising frontier for energy-efficient spin manipulation, the control of topological magnetism remains challenging due to its scarcity in multiferroics. Here, we demonstrate that highly tunable merons and antimerons emerge in monolayer multiferroic (CCPS). The antiferroelectric-to-ferroelectric (AFE-FE) transition enhances exchange couplings, notably reducing meron density and increasing meron size during cooling. Merons exhibit unique dynamics, characterized by nontrivial attraction and annihilation processes, which generates distinct long-lived spin waves and reduces meron number difference between AFE and FE phases until they vanish. Importantly, ultrafast laser pulses can induce ferroelectricity-tunable merons from a uniform in-plane magnetization, re-leading to a large difference in meron density between the AFE and FE phases. These findings enhance our understanding of topological magnetism and open up exciting avenues for controlling the properties and dynamics of topological states through electrical and optical methods.