Tunneling magnetoresistance and spin–valley polarization in 8-Pmmn borophene-based ferromagnetic junctions

Traditional magnetic tunnel junctions consist of two ferromagnetic layers separated by a thin insulating barrier. This configuration has been widely studied due to its ability to exhibit tunneling magnetoresistance (TMR). Here, in this work, we explore two different ferromagnetic tunnel junctions based on 8-Pmmn borophene. The junctions were generated with the help of ferromagnetic (FM), non-magnetic (NM), and a ferromagnetic insulator (FI) arranged as FM–NM–FI and FM–FI–NM. Positive and negative magnetizations in the FI region give rise to parallel and antiparallel configurations. The results show that the FM–NM–FI junction exhibits perfect regions of positive and negative spin polarization in the parallel and antiparallel configurations. Likewise, TMR reaches a positive saturation value close to 100%. The FM–FI–NM junction shows perfect spin polarization regions that can be modulated by increasing the magnetization strength. Furthermore, the TMR presents positive and negative values. Neither junction shows valley polarization. Applying an external magnetic field in the central region breaks the symmetry in the conductance components of the K and K′ valleys, allowing the emergence of valley polarization.