Ferroelectric control of spin filtering in a multiferroic CuCrP ₂ S ₆ tunnel junction

Abstract CuCrP ₂ S ₆ (CCPS), a van der Waals multiferroic material, offers a promising platform for electrically controlled spin-filter tunnel junctions by combining switchable electric polarization and layered magnetism within a single barrier. Here, using density functional theory combined with nonequilibrium Green’s-function calculations, we investigate spin-dependent transport in an Au/CCPS/Au junction and demonstrate non-volatile electric control of spin-dependent tunneling via polarization-induced modulation of the tunneling barrier. The antiferroelectric phase of CCPS supports highly efficient spin filtering, yielding nearly 100% spin polarization and a giant thickness-dependent tunneling magnetoresistance (TMR) of approximately 3100% for 4-layer CCPS. In contrast, in the ferroelectric phase, polarization-driven interfacial charge transfer reduces the spin asymmetry of the barrier, lowering the spin polarization to ∼67% and suppressing the TMR to ∼48%. Momentum-resolved transmission and complex-band analysis reveal that this reduction originates from competing spin-dependent evanescent states across the two-dimensional Brillouin zone. Calculated current-voltage characteristics exhibit distinct, experimentally accessible signatures of polarization-controlled spin filtering, establishing CCPS as a compelling platform for electrically tunable spintronic devices.