Enhanced spin-transfer torque in asymmetric superlattice magnetic tunnel junctions with engineered barrier profiles

We systematically investigate charge current dynamics and spin-transfer torque (STT) in asymmetric superlattice magnetic tunnel junctions (MTJs) featuring distinct ferromagnetic electrodes: CoFeB and La_0.7Sr_0.3MnO₃. They incorporate both regular and engineered barrier-height profiles. The profiles include linear, Gaussian, Lorentzian, Pöschl-Teller, and anti-reflective designs. We use the non-equilibrium Green’s function formalism within the effective-mass tight-binding framework. STT is quantitatively evaluated under applied bias conditions. The study reveals that asymmetric MTJs exhibit marked enhancement in spin-transfer torque compared to symmetric counterparts. This improvement results from the interplay of asymmetric magnetization magnitudes and orientations. Custom barrier profiles optimize spin-polarized current transmission and angular momentum transfer. These findings deepen understanding of spin-dependent transport in complex MTJ architectures. These results highlight a promising pathway for advancing spintronic device performance, particularly in applications requiring efficient magnetization switching and low-power operation. The demonstrated approach offers a compelling strategy for designing next-generation spintronic components by leveraging structural asymmetry and barrier engineering to achieve superior STT efficiencies.