Suppressing Metallization in MoS₂ for Enhanced Negative Magnetoresistance

Spintronics harnesses the intrinsic spin of electrons to enable next-generation devices, and 2D materials have emerged as key players in advancing this technology due to their unique electronic and magnetic properties. Among these materials, MoS₂ stands out for its ability to provide a more selective tunneling mechanism compared to traditional oxide barriers (e.g., Al₂O₃, MgO) in magnetic tunnel junctions (MTJs), owing to its superior energy alignment for minority spins. Furthermore, MoS₂-induced perpendicular magnetic anisotropy (PMA) in ferromagnetic metals positions it as a promising spacer for spin-transfer torque (STT) MTJs. Despite these advantages, the performance of MoS₂-based MTJs is hindered by strong band hybridization with adjacent ferromagnetic layers, leading to metallization of MoS₂, reduced magnetoresistance (MR), and overall performance degradation. To overcome this challenge, we integrated multilayer MoS₂ to effectively suppress metallization effects. Leveraging the previously developed Uninterrupted Contact Deposition (UCD) method, we achieved pristine, contamination-free interfaces, enhancing overall device performance. Magnetic measurements revealed record-breaking negative MR, consistent with theoretical models, alongside the presence of PMA in multilayer MoS₂-based MTJs. Notably, temperature-dependent studies exhibited an unexpected rise in the MR ratio between 250–400 K, attributed to phonon-assisted conduction. This defies conventional expectations of thermal disruption to spin alignment, highlighting the unique spin transport properties associated with MoS₂’s indirect bandgap. Our findings unlock the potential of MoS₂ as an effective spin-filter in MTJs, offering a substantial performance enhancement for spintronic devices driven by quantum tunneling mechanisms.