Large tunneling magnetoresistance and perpendicular magnetic anisotropy in magnetic tunneling junction based on spin gapless semiconductor CoFeCrAl

Spin gapless semiconductors (SGSs) have drawn increasing attention in spintronic materials for their complete spin polarization and ability to reduce conductance mismatch. Motivated by the recent synthesis of SGS CoFeCrAl (CFCA) with a high Curie temperature (575.2 K) and the magnetic tunnel junction (MTJ) based on the CFCA electrode, we utilized density functional theory combined with the nonequilibrium Green's function method to investigate the magnetic anisotropy energy of the CFCA/MgO heterostructure and the spin transport properties of the CFCA/MgO/CFCA MTJ, with a comparative analysis against the experimentally fabricated CoFe/MgO/CFCA MTJ. Our findings demonstrate that the CoFe-O interface configuration is the most stable and shows a considerable interfacial perpendicular magnetic anisotropy (PMA) of 0.69 mJ/m², with its origin elucidated through layer- and orbital-resolved analysis. More intriguingly, the CFCA/MgO/CFCA MTJ exhibits a large tunnel magnetoresistance (TMR) of 1.3 × 10⁷%, resulting from the interfacial spin filtering. Additionally, we reveal that the TMR of CoFe/MgO/CFCA MTJ is only 1.56 × 10³% due to mismatched wave function distribution between the left and right electrodes. These findings provide a comprehensive understanding of the PMA and TMR, indicating that CFCA is a promising SGS material for spintronic applications.