Interface-driven spin filtering and diode effects in van der Waals junctions based on magnetic metal-organic frameworks

Abstract

Modulating the interface between the molecule and electrode is an effective way to enhance the spin-polarized transport properties of molecular junctions. In this study, using first-principles calculations combined with the nonequilibrium Green’s function method, we demonstrate that the spin-transport properties of Cr(pyz)₂ (pyz = pyrazine)-based van der Waals junctions can be significantly regulated by the tunneling barrier and dipole between the molecule-electrode interface. Specifically, we find that the charge transfer and redistribution process within Cr(pyz)2 can arise a transition from a semiconductor to a half-metal in the tunneling junction, leading a notable enhancement of spin filtering efficiency (SFE). Besides, partial fluorination of Cr(pyz)₂ has also be demonstrated to effectively enhance the electronegativity of the structure, facilitate the formation of dipole moments within the molecule and at the molecule-metal interface, and induces diode-like behavior. Our results highlight the potential of interface-driven spin filtering and diode effects in Cr(pyz)₂-based van der Waals junctions, paving the way for spintronics device design.