• CoPd ultrathin films with low Co content and perpendicular magnetic anisotropy. • Chemical stability and compositional gradient of electrodeposited CoNiPd films. • Narrow switching-field distribution in electrodeposited CoNiPd ultrathin films. The rapidly growing demand for information processing has highlighted current-induced magnetization switching as an ultrafast writing method that is also suitable for high-density integration, making it a promising writing method for next-generation magnetic memory devices. In this context, this study aimed to develop ultrathin CoPd and CoNiPd films via electrodeposition with perpendicular magnetic anisotropy (PMA) and low saturation magnetization ( M s ), which are desirable for current-induced magnetization switching devices. We conducted electrodeposition using a Pd 2+ -rich solution and fabricated approximately 3−4 nm-thick CoPd ultrathin films on fcc(111)-oriented Pt substrates with exceptionally low Co content (10–30 at.%), exhibiting PMA and M s lower than previously reported values. However, the films also exhibited high coercivity ( H c ), which could hinder current-induced magnetization switching. To improve this, Ni was introduced into CoPd and it was confirmed that H c decreased monotonically with increasing Ni content, demonstrating that the magnetic properties could be tuned by adjusting the Ni composition while preserving low M s , high squareness, and coherent magnetization switching. Additionally, the Co atoms in the films exhibited high chemical stability. Compositional depth profiling further revealed a gradient structure, which could be beneficial as a structural basis for exploring field-free spin-orbit torque magnetization switching. These results demonstrate that electrodeposition enables the fabrication of ultrathin films as a materials platform for current-induced magnetization switching devices and that their magnetic properties can be easily tuned. Thus, the present results provide materials-level guidance and a foundation for future device-level investigations of current-induced magnetization switching.
Suzuki et al. (Fri,) studied this question.