Study of the origin of orientation ratio in high-density longitudinal magnetic recording media

Abstract

A study on the origin of orientation ratio (O.R.) in high-density recording media on mechanically textured substrates is reported. -axis distribution of Co grains in textured case observed using high resolution transmission electron microscopy (HRTEM) images shows its preferred orientation along the circumferential (along the groove) direction. The asymmetrical easy axis distribution is seen by maximum torque observed in different directions along the plane of the film. Diffraction patterns from several individual grains of the Cr under-layer are analyzed and indicated the preference of Cr 110 along the circumferential direction. This could be the reason for -axis of Co grains to show the preferred anisotropy along circumferential direction.Index Terms-Longitudinal magnetic recording media, mechanical texturing, orientation ratio.

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

“…This near constant value indicates the c-axis distribution as the cause of OR, as mentioned previously. This result is thus consistent with the TEM observation [2][3][4] and also the specific Cr orientation mentioned previously. Since the OR is determined by measuring the coercivity, thermal effects sets in when the thickness or grain sizes are smaller.…”

“…It was pointed out that this predominant orientation of the c-axis may be due to a particular nucleation of Cr. 3 In this letter, we explain in detail how this particular growth of Cr was observed, which in turn helps the orientation of Co͓0002͔ along the circumferential direction and gives rise to an OR. We have also studied the OR with respect to temperature to understand the mechanism of in-plane magnetic anisotropy.…”

“…Although the origin of OR is so far not clearly understood, interesting studies have been reported which are beneficial for the future development of magnetic recording. [1][2][3][4] The two possible main mechanisms, suggested for this in-plane magnetic anisotropy, are stress on the magnetic layer, 1 and the c-axis ͑Co͓0002͔ direction͒ preference of orientation along the groove direction. 2,3 However, there are no explanations for this particular predominant c-axis orientation of the Co grains in the magnetic layer along the mechanical groove direction.…”

Electrochemical Synthesis of Metal Alloys for Magnetic Recording Systems

“…À2 [6], and demonstration of 170 Gbits Á in. For a perpendicular medium, the sputter deposition of CoCr alloy film, which was first reported by Iwasaki and Ouchi [10], and the control of grain orientation, grain size, and magnetic properties of film also have contributed to the progress in areal density [9][10][11][12]. However, there has been an apparent slowdown in this increase of density.…”

Effect of media textured surface on defect and noise in hard disk

“…The super-smooth surface is typically obtained by a well-controlled circumferential texturing process using diamond slurries combined with texturing tape. Media defect and magnetic recording properties are strongly related to texture surface topography, such as texture line density and depth, and stock removal rate of substrate surfaces [1,2]. The orientation ratio (OR) is a parameter that characterizes the directional preference of the magnetic properties of a recording media [3,4].…”