Ferromagnetic-like spin splitting induced tunneling magnetoresistance and exchange bias in fully compensated ferrimagnetic tunnel junctions

Abstract

Achieving giant tunneling magnetoresistance (TMR) in antiferromagnetic (AFM) tunnel junctions remains a central challenge in AFM spintronics. Conventional antiferromagnets suffer from insufficient spin polarization due to spin degeneracy, which severely limits further readout of magnetic states. Here, we propose exploiting the ferromagnetic-like spin splitting in filling-enforced fully compensated ferrimagnets (fFIMs) to realize giant TMR in a simple bilayer van der Waals tunnel junction based on NiICl/CrI3. First-principles calculations reveal that NiICl exhibits spin-polarized bands near the Fermi level similar to those of ferromagnets, thereby overcoming the momentum-space limitation of conventional antiferromagnets. Leveraging the pronounced spin polarization of NiICl, the tunnel junction achieves a giant TMR of up to 2.065 × 104% around the Fermi level. Further investigation shows that strong exchange coupling at the NiICl/CrI3 interface induces an exchange-bias field of 0.765 T, which stabilizes the ferromagnetic layer against external perturbations and is beneficial for reliable device operation. This work highlights the unique advantages of ferromagnetic-like spin polarization in fFIMs and provides an alternative approach for designing structurally simple and high-performance spintronic devices.