In conventional ferromagnetic tunnel junctions, the tunnel magnetoresistance (TMR) typically increases with increasing barrier thickness under ballistic tunneling conditions. In contrast, the authors reveal here unconventional scaling behavior in altermagnetic tunnel junctions, where the TMR decreases as the barrier becomes thicker. This trend originates from spin-degenerate transmission channels inherent to altermagnets, which effectively suppress the increase of TMR with increasing barrier thickness.
Yang et al. (2025) studied this question.