Contact engineering and tunable ferromagnetism in MoSeF/2D metal van der Waals heterostructures

Two-dimensional (2D) long-range magnets have significantly advanced the development of ultra-compact non-volatile spintronic devices. Their functionality, however, can be limited by Fermi-level pinning (FLP), magnetic phase-transition temperature, and interfacial electrostatic barriers. Addressing these challenges requires an atomic-scale understanding of the electronic and magnetic reconstruction at van der Waals magnetic interfaces. Here, we investigate a series of van der Waals heterojunctions formed between 2D metals and a ferromagnetic Janus MoSeF monolayer. The calculations reveal that metal contacts can effectively weaken the FLP effect in MoSeF-based vdW heterojunctions. Further analysis shows that the weakened pinning is associated with metal-dependent interfacial potential steps (Δ V ) arising from charge redistribution and interface-dipole formation. The interfacial electrostatic reconstruction also modifies the effective tunneling barriers across the vdW gap, which are used here as qualitative descriptors of the relative tunneling tendency. Orbital-resolved analysis further reveals that metal contacts induce spin-dependent reconstruction of Mo- d states, particularly the d xz/yz orbitals, accompanied by hybridization with transition-metal- d and interfacial chalcogen- p states, thereby contributing to the modulation of the exchange interaction J and Curie temperature ( T c ). Notably, the MoSeF/VSe 2 heterojunction exhibits a T c of up to approximately 449 K, nearly twice that of freestanding monolayer MoSeF (210 K ). These results provide atomic-scale insight into the simultaneous tuning of electronic contact characteristics and magnetic properties in Janus MoSeF-based vdW heterostructures.