Sliding ferroelectric metal with ferrimagnetism

In this work, we develop a general strategy for constructing two-dimensional sliding ferroelectric ferrimagnetic metals from antiferromagnetic metallic bilayers, achieving triply-coupled switching in which the ferroelectric polarization, spin splitting, and net magnetic moment are simultaneously reversed via ferroelectric switching. As a prototype, we design a sliding bilayer ferroelectric metal with ferrimagnetic order based on Fe₅GeTe₂, a van der Waals ferromagnet near room temperature. The system undergoes a ferroelectric phase transition from a nonpolar antiferromagnetic phase to a ferroelectric ferrimagnetic phase driven by relative interlayer sliding. The breaking of in-plane mirror symmetry in the ferroelectric metallic states lifts the non-relativistic spin degeneracy present in the nonpolar phase, resulting in a sizable net magnetic moment. Moreover, the coexistence of metallic conductivity, ferroelectricity, and ferrimagnetism gives rise to pronounced sign-reversible transport responses near the Fermi level, all of which can be electrically modulated through ferroelectric switching.