Perpendicularly Magnetized Ni / Pt (001) Epitaxial Superlattice

A perpendicularly magnetized ferromagnetic layer is an important building block for recent/future highdensity spintronic memory applications. This paper reports on the fabrication of perpendicularly magnetized Ni / Pt superlattices and the characterization of their structures and magnetic properties. The optimization of film growth conditions allowed us to grow epitaxial Ni / Pt (001) superlattices on SrTiO$_{3}$ (001) single crystal substrates. We investigated their structural parameters and magnetic properties as a function of the Ni layer thickness, and obtained a high uniaxial magnetic anisotropy energy of 1.9 x 10$^{6}$ erg/cm$^{3}$ for a [Ni (4.0 nm) / Pt (1.0 nm)] superlattice. In order to elucidate the detailed mechanism on perpendicular magnetic anisotropy for the Ni / Pt (001) superlattices, the experimental results were compared with the first-principles calculations. It has been found that the strain effect is a prime source of the emergence of perpendicular magnetic anisotropy.