Enhancement of perpendicular magnetic anisotropy in W/Co/Pt films by nitrogen doping in the W layer

The modulation of perpendicular magnetic anisotropy (PMA) in films has been the subject of considerable research interest, as it is proposed to be a key component for the design and realization of efficient magnetic switching in spintronic devices. In this study, we report the appearance of PMA in the as-deposited WN_x/Co/Pt films without annealing. The strength of the PMA is quantified by means of effective magnetic anisotropy constant K_eff, which is correlated with the N₂ gas/Ar gas flow rate ratio $P N 2$⁠. The highest K_eff value, 1.347 × 10⁶ erg/cm³, is obtained for the sample deposited with $P N 2$ of 40%. This phenomenon can be explained in two ways. On the one hand, the results of the experiment demonstrate that appropriate nitrogen doping can facilitate the formation of an ideal nitrided state at the WN_x/Co interface, while simultaneously reducing the roughness of the WN_x/Co interface, which, in turn, enhances the PMA of the WN_x/Co/Pt films. On the other hand, the first-principles calculations indicate that the enhancement of PMA can be attributed to the modification of orbital hybridization at the Co/Pt interface by WN_x. This innovative approach has the potential to advance the development of high-performance magnetic random-access memory devices.