SmCo/Cr bilayer films for high-density recording media

Abstract

The magnetic properties of a SmCo layer on a Cr underlayer, which was prepared by various Ar gas pressure (PAr), were studied. A single line appeared in each X-ray diffraction diagram and its intensity became strong when PAr was decreased from 1.06 to 0.13 Pa. The microstructure observed by using atomic force microscopy showed that the surface morphological structure of Cr underlayers depended on PAr and the surface of the Cr underlayer became smoother as PAr was decreased, while the surface and the grain of the SmCo layer on the Cr underlayer were independent of PAr. The grain size of SmCo layers was as small as 30 nm with the surface roughness of about 1 nm. The coercivity, the squareness ratio, and the coercivity squareness ratio of the SmCo layer on the Cr underlayer prepared at 0.13 Pa were 155 kA/m, 0.92 and 0.92, respectively. Those values suggest that an easy axis of magnetization for the SmCo layer is in plane and the switching field distribution is very small. Although the crystal structure of the SmCo layer has not been clarified yet, it was found that the magnetic properties of SmCo layers can be controlled by the crystal structure of the Cr underlayer and SmCo/Cr bilayer films are promising materials for the ultrahigh density recording media.

Sm–Co films for high-density magnetic recording media

“…Such grains can theoretically support the recording density up to 10 Tb/in 2 . The Sm-Co films have long been studied as a longitudinal recording medium [2,3]. Recently, Sm-Co films with perpendicular anisotropy have been considered as prominent candidates for future ultra high-density perpendicular medium [4,5].…”

Magnetic properties of Dy(Tb)Co/Cr thin films for hybrid recording

“…When sputtering at 375 W and 4 mT, the composition for the TbCo layer was Tb 31 Co 69 which was confirmed by EDX. On the other hand, since the grain size and the morphology of the Cr underlayer is very sensitive to argon pressure, and the microstructure of the underlayer will directly affect the microstructure of the magnetic layer (Takei et al 1997), varying the sputtering pressure of the Cr underlayer will be result in a change of the coercivity of the TbCo films. So a number of films were prepared where the sputtering conditions for the TbCo magnetic layer were kept constant at 375 W, 4 mTorr and 3 min.…”

Film Composition, Substrate Temperature, and Thickness Dependence of Sm(Co, Cu)$_{5}$/Ru Thin Films With Perpendicular Anisotropy

“…In the past, many researchers reported the fabrication of Sm-Co films with in-plane anisotropy [6]- [13]. Recently, SmCo thin films with perpendicular anisotropy were obtained on a Cu underlayer [14]- [18].…”