Efficient spin filtering through Fe₄GeTe₂-based van der Waals heterostructures

Utilizing ab initio simulations, we study the spin-dependent electronic transport characteristics within Fe₄GeTe₂-based van der Waals heterostructures. The electronic density of states for both free-standing and device-configured Fe₄GeTe₂ (F4GT) confirms its ferromagnetic metallic nature and reveals a weak interface interaction between F4GT and PtTe₂ electrodes, enabling efficient spin filtering. The ballistic transport through a double-layer F4GT with a ferromagnetic configuration sandwiched between two PtTe₂ electrodes is predicted to exhibit an impressive spin polarization of 97% with spin-up electrons exhibiting higher transmission probability than spin-down electrons. Moreover, we investigate the spin transport properties of Fe₄GeTe₂/GaTe/Fe₄GeTe₂ van der Waals heterostructures sandwiched between PtTe₂ electrodes to explore their potential as magnetic tunnel junctions in spintronic devices. The inclusion of monolayer GaTe as a 2D semiconducting spacer between F4GT layers results in a tunnel magnetoresistance of 487% at a low bias and decreases with increasing bias voltage. Overall, our findings underscore the potential of F4GT/GaTe/F4GT heterostructures in advancing spintronic devices based on van der Waals materials.