Heavy-Metal-Free, Low-Damping, and Non-Interface Perpendicular Fe₁₆N₂ Thin Film and Magnetoresistance Device

Realization of sub-10 nm spin-based logic and memory devices relies on the development of magnetic materials with perpendicular magnetic anisotropy that can provide low switching current and large thermal stability simultaneously. In this work, the authors report on one promising candidate, Fe₁₆N₂, a heavy-metal-free, non-interface perpendicular magnetic material and demonstrate a perpendicularly magnetized current-perpendicular-to-plane (CPP) giant magnetoresistance (GMR) device based on Fe₁₆N₂. The crystalline-based perpendicular anisotropy of Fe₁₆N₂ in the CPP GMR device is measured to be about 1.9 × 10⁶ J m⁻³ (1.9 × 10⁷ erg cm⁻³), which is sufficient to maintain the thermal stability of sub-10 nm devices. A first principle calculation is performed to support this large magnitude of the perpendicular anisotropy. Moreover, the Gilbert damping constant of the Fe₁₆N₂ thin film (α ≈0.01) measured by ferromagnetic resonance (FMR) is lower than for most existing materials with crystalline perpendicular magnetic anisotropy. The non-interface perpendicular anisotropy and low damping properties of Fe₁₆N₂ may offer a pathway for future spintronics logic and memory devices.