Thermally Driven Spin Filtering Effect and Large Tunnel Magnetoresistance Based on Half‐Metallic NiMnSb

Half‐metals are promising candidates for spintronic applications due to the complete spin polarization at the Fermi level. Recently, ferromagnetic half‐metallic NiMnSb has regained considerable research attention owing to its nontrivial topological properties. For example, Singh et al. found that the Weyl node in NiMnSb produces anomalous Hall conductivity [ Adv. Sci. 11, no.31 (2024): 2 404 495]. In this work, we design an AlAs/NiMnSb heterostructure and a magnetic tunnel junction (MTJ) NiMnSb/AlAs/NiMnSb to explore the potential spintronic applications of half‐metallic NiMnSb. Density functional theory combined with non‐equilibrium Green's function method reveals that the heterostructure exhibits an ideal thermal spin filtering effect and a spin diode effect. In addition, the MTJ has a large tunnel magnetoresistance ratio up to 3.7 × 10 5 % at room temperature. These phenomena can be understood from the spin‐dependent band structure and transmission spectrum. These results highlight the promising potential of NiMnSb for spintronic devices.