Optimizing magneto-ionic performance in structure/composition-engineered ternary nitrides
Résumé
Magneto-ionics, an emerging approach to manipulate magnetism that relies on voltage-driven ion motion, holds the promise to boost energy efficiency in information technologies such as spintronic devices or future non-von Neumann computing architectures. For this purpose, stability, reversibility, endurance, and ion motion rates need to be synergistically optimized. Among various ions, nitrogen has demonstrated superior magneto-ionic performance compared to classical species such as oxygen or lithium. Here, we show that ternary Co 1Àx Fe x N compound exhibits an unprecedented nitrogen magnetoionic response. Partial substitution of Co by Fe in binary CoN is shown to be favorable in terms of generated magnetization, cyclability and ion motion rates. Specifically, the Co 0.35 Fe 0.65 N films exhibit an induced saturation magnetization of 1,500 emu/cm 3 , a magneto-ionic rate of 35.5 emu/(cm 3 $s) and endurance exceeding 10 3 cycles. These values significantly surpass those of other existing nitride and oxide systems. This improvement can be attributed to the larger saturation magnetization of Co 0.35 Fe 0.65 compared to individual Co and Fe, the nature and size of structural defects in as-grown films of different composition, and the dissimilar formation energies of Fe and Co with N in the various developed crystallographic structures.
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