Controllable topological phase transition via ferroelectric–paraelectric switching in a ferromagnetic single-layer MIMIIGe2X6 family

undergoes a transformation from PE to FE by overcoming the energy barrier of 0.62 eV, subsequently realizing the phase transition from the Weyl semimetal to the high order topological insulator. These findings not only combine topological states with multiferroics but also pave the way for the experimental discovery of 2D tunable topological phase transition.