Effect of top Ru deposition pressure on magnetic and microstructural properties of CoCrPt–SiO2 media in two-step Ru layer

Abstract

Articles you may be interested inEffect of RuCoCr-oxide intermediate layers on the growth, microstructure, and recording performance of CoCrPt -SiO 2 perpendicular recording media Two-step-deposited Ru layers of 20 nm have been employed as an underlayer for CoCrPt-SiO 2 perpendicular magnetic recording media. The bottom Ru layer of 10 nm is deposited at 3 mTorr for good texture of hcp ͑0002͒ and the top Ru layer of 10 nm is deposited at various conditions. Sputtering power and Ar pressure are variables for the top Ru layer deposition. As the sputtering pressure of the top Ru layer increases, coercivity ͑H c ͒ of the CoCrPt-SiO 2 layer increases and then saturates or slightly decreases with a further increase of sputter pressure. The H c increase is mainly due to exchange decoupling among grains of CoCrPt. The c-axis alignment of the Ru layer by the two-step deposition method is much improved compared to that of a single-step-deposited Ru layer when the sputtering pressure is higher than 3 mTorr. The grain size of Ru layer is smaller and the grains are well separated by void boundaries when the top Ru sputtering pressure is high. There is a one-to-one relationship between small Ru grains and CoCrPt grains. Although the grain size of CoCrPt layer is small with a good c-axis alignment in the case of lower-pressure-deposited top Ru underlayer, H c is small. The reason will be discussed in terms of grain interconnection.

Thermal stability and the magnetization process in CoCrPt–SiO2 perpendicular recording media

“…The excellent recording performance of media is due to combination of good microstructural and magnetic properties such as-small grain size, square hysteresis loops, low noise, high anisotropy, and improved thermal stability-among others [1][2][3][4][5][6][7]. Compared to the previous generation of HDD that used longitudinal recording media with random inplane crystallographic texture, a key requirement for the HDD based on perpendicular recording media is in the substantial degree of out-of-plane crystallographic texture that is necessary to achieve high signal-to-noise ratios.…”

Microstructure and switching mechanism of stacked CoCrPt–SiO2 perpendicular recording media

“…CoCrPt-oxide-based perpendicular recording layers (RL) are currently used in the hard disk drives owing to their small grain size, square hysteresis loops, low noise, high anisotropy, and improved thermal stability-among others [1][2][3][4][5][6][7][8][9][10][11][12][13]. In order to magnetically isolate the RL grains and shrink grain sizes further, several routes such as dopants, increased oxygen content and high gas pressure sputtering of the media layer, or of the intermediate layers (IL) have been proposed in the past [5,6,[11][12][13].…”

Intermediate layer thickness dependence on switching field distribution in perpendicular recording media

“…When the thickness of the RuCr layer is reduced, the exchange coupling between the grains of the recording layer increases leading to a reduced H c and H n . The maximum H c is obtained at the minimum exchange slope, as revealed by Park et al [17]. To study the intrinsic SFD, major and minor recoil loops were measured for all the samples reported in Table 1.…”

“…In this paper, we used DH(M, DM) method described in Ref. [6] to evaluate the intrinsic SFD. This method is based upon comparison between the major loop and the set of recoil loops starting at certain position DM away from saturation magnetization, M S .…”

“…In such PMR media, an additional nonmagnetic intermediate layer (IL) such as Ru, with a thickness in the range 10-20 nm is used to exchange decouple the soft underlayer (SUL) and the recording layer. This IL can also be utilized to provide crystallographic c-axis orientation and grain isolation for the recording layer [4][5][6][7]. In addition, the IL can be exploited for grain size reduction in the recording layer [8].…”