Crystallographic orientation of Cr in longitudinal recording media and its relation to magnetic anisotropy

Abstract

A specific growth of Cr layer grains is found to exist when grown on the mechanically textured NiP–Al substrates used for longitudinal recording. High resolution transmission electron microscopy analysis of a large number of individual Cr grains indicate a Cr[110] preferential growth along the textured direction (groove or circumferential direction). This particular orientation of the Cr underlayer is found to be the cause of an in-plane magnetic anisotropy of the Co based magnetic layer. The temperature dependence of this in-plane magnetic anisotropy study indicated the importance of the specific crystallographic orientations of both the underlayer and the magnetic layer.

Perpendicular recording media for hard disk drives

“…For the longitudinal recording media, such a partially ordered arrangement of easy axes was obtained as an unexpected consequence of the mechanical texturing process. 54 Figure 3 illustrates the magnetization orientation for dif- ferent media configurations. However, it was observed from the hysteresis loops of mechanically textured substrates that the recording media could show different coercivities ͑H c ͒ and remanent moments ͑M r ͒ when measured along the track or radial direction ͑along or in the transverse direction of the texture lines, respectively͒.…”

Recording media research for future hard disk drives

“…The latter is the ratio of H c in the circumferential to that in the radial direction, and was brought about by a mechanical texturing process. Experimental studies on oriented media are yet to clarify as to what causes the OR [7][8][9][10]. It may be worthwhile to carry out film growth simulations of Cr underlayer and a Co-alloy recording layer (RL) on textured and non-textured substrates, to understand the real cause of preferred orientation along the track direction.…”

Oblique Ion Nano-Texturing Technology for Longitudinal Recording Media

“…[1][2][3] Figure 5 shows (a) a high-resolution TEM image and (b) an FFT pattern of a Co-Cr-Pt-B alloy grain on the substrate shown in Fig. 2.…”

“…Texturing formed by grooves in the circumferential direction on a disk substrate is used with the intention to point the magnetic easy axes of Co alloy grains in the same direction 1,2) and consequently improve signal-to-noise ratio (SNR) and thermal stability. In current mechanical texturing processes, a substrate surface is rasped in the circumferential direction with fiber tape and a diamond slurry.…”