Observing and Suppressing Metallization in MoS₂ for Near-Ideal Spin Filtering

Two-dimensional (2D) transition-metal dichalcogenides (TMDCs) offer band alignments that are well-suited for minority-spin filtering when interfaced with ferromagnets. Unfortunately, interfacial hybridization results in the emergence of metallic states in MoS₂ that have limited previous results significantly below theoretical expectations. Here, we study the metallization at the Co/MoS₂ interface and devise a method to overcome its detrimental impact on spin transport. Using a contamination-free fabrication process, clear evidence of hybridization was observed, which increases the magnetic anisotropy of the interface. Magneto-transport and theoretical analysis reveal that the metallic wave functions extend into the MoS₂ layer, suppressing its ability as a filter barrier. The spin-filtering ability can be restored when separating the MoS₂ by only two atomic layers. The resulting device achieves a record tunneling magnetoresistance (TMR) of -170.2%, consistent with simulations of ideal minority spin filtering. Temperature-dependent measurements further distinguish two dominant transport regimes, spin injection at low temperatures and spin-dependent tunneling at higher temperatures. The combined contribution of these mechanisms sustains high TMR across the full temperature range. Our findings establish a path for realizing scalable, high-performance 2D spintronic devices for applications in MRAM, spin logic, and magnetic sensing.