Unpinning the magnetic interface between 2D materials and NiFe for ultra-low coercivity spin valves

The integration of two-dimensional (2D) materials into spintronic devices could enable unconventional computing paradigms, such as stochastic computing, that surpass CMOS in energy efficiency and device density. However, their implementation has faced unexpectedly high coercivity values, increasing the energy cost of magnetic switching. Here, we investigate the origin of this magnetic pinning at the interface between ferromagnetic NiFe and graphene. Vertical spin valves were fabricated using an Uninterrupted Contact Deposition (UCD) technique that prevents interfacial oxidation and contamination. The resulting near-pristine devices exhibit a 25-fold reduction in coercivity, approaching the intrinsic limit of NiFe, as confirmed by magneto-optical and Hanle effect measurements. The importance of suppressing antiferromagnetic exchange bias was highlighted through the introduction of a remote NiO interface that dominates the device’s magnetic anisotropy. These findings establish the intrinsic behavior of 2D spintronic interfaces and clarify the spin-transport mechanism in graphene, offering a platform for future low-power spin-based logic.