Pawel Glijer

Effects of platinum content and substrate bias on the structure and magnetic properties of CoCrPt/Cr thin films

The effects of the Pt content (0–40 at. %) and the developed dc substrate bias voltage (0 to −190 V) on the magnetic properties and structure of rf sputtered CoCrPt/Cr films with two different remanent magnetization‐thickness products Mrδ (0.7 and 2.3 memu/cm2) were studied. It was demonstrated that a wide range of in‐plane coercivities (500–3450 Oe) can be easily obtained in these films. The addition of Pt affected the magnetic properties of the films through changes of the lattice parameter, texture, and phase composition. A maximum in the in‐plane coercivity exists for moderate amounts of Pt. The saturation magnetization decreased monotonically with increasing Pt content. rf substrate bias increased the in‐plane coercivity and altered the character of the magnetic interactions through changes of the stress, texture and microstructure of the magnetic layer.

Magnetic force microscopy (MFM) studies of micromagnetic structures of high coercivity CoCrPt/Cr and CoCrPtB/Cr thin films

The magnetic microstructures of high coercivity CoCrPt/Cr and CoCrPtB/Cr films were investigated using magnetic force microscopy (MFM). Experiments show that the MFM technique can be used for both qualitative and quantitative description of the magnetic microstructure of high coercivity films for magnetic recording media. It was found that the magnetic microstructure was more refined for films with higher coercivity. The roughness of the magnetic images tend to decrease with increasing coercivity and decreasing media noise. Magnetic images obtained for films with ac-erased state consisted of rounded, symmetric features indicating presence of magnetic vortices. Images from samples in remanent coercivity state showed elongated transitions between regions with different magnetization direction.

Comparison of reproduce signal and noise of conventional and keepered CoCrTa/Cr thin film media

We studied keepered high coercivity CoCrTa/Cr thin film media with a Cr isolation layer between the CoCrTa storage and an overcoating of an isotropic NiFe soft magnetic layer. The influence of the thickness of the NiFe and Cr layers, and the effects of head bias current on the signal output and noise, were studied using a thin film head. The reproduced signal increased by 7.3 dB, but the signal‐to‐noise ratio decreased by 4 dB at a linear density of 2100 fr/mm (53.3 kfr/in.) with a 1000 A thick NiFe keeper layer. The medium noise increased with increasing NiFe thickness and the signal output decreased with decreasing Cr thickness. A low output signal obtained with very thin Cr may be due to magnetic interactions between the keeper layer and magnetic media layer. It is observed that signal distortion and timing asymmetry of the output signals depend on the thickness of the keeper layer and the head bias current. The signal distortion increased and the timing asymmetry decreased as the head bias current was...

Magnetic force microscopy studies of ultrahigh density magnetic recording on longitudinal and perpendicular media

It has been demonstrated using magnetic force microscopy (MFM) that magnetic recording patterns with linear densities in excess of 230 kfci can be sustained by isotropic longitudinal media with H/sub c/=2500 Oe and perpendicular media with H/sub c/=1800 Oe. It was found that the size of magnetic cluster domains limited the linear recording density sustainable by a longitudinal medium and that the cluster size decreased with increasing medium coercivity. As the bit size approached the minimum cluster size observed in the magnetic background of longitudinal medium, the bits tended to percolate within the track resulting in a complete disappearance of a recorded pattern. In the case of the perpendicular medium, the bit transitions remained sharp at high densities. As the bit size approached minimum cluster domain size, the signal amplitude approached the noise amplitude thus limiting the detectability of the recorded bit pattern.

Electron energy loss spectroscopy studies of CoCrTaPt/Cr thin films for high-density longitudinal magnetic recording media

Abstract The effects of Ta content in CoCrTaPt thin films on the near-edge structure of Co and Cr L2.3 absorption edges have been studied using parallel electron energy loss spectroscopy (PEELS). It was found that the addition of Ta decreased the 3d band occupancy in CoCrTaPt thin films. The addition of Ta was also observed to decrease the L3/L2 white line intensity ratio, which showed a qualitative correlation with Curie temperature measurements. This result indicates a decrease in the ferromagnetic exchange interaction between neighboring Co atoms which may account for the low noise of CoCrTaPt thin film media.

Structural design of CoCrPt(Ta,B)/Cr magnetic thin film media for ultra high density longitudinal magnetic recording

CoCrPt(Ta,B) thin films with Cr underlayers were studied as potential candidates for ultra-high density magnetic recording media for data storage at 10 Gbits/inch2. The experimental approach used was aimed at an analysis of the structure-properties relationships in these thin films. As a result structural and composition changes resulting in magnetic and noise properties have been identified. It has been shown that very high in-plane coercivities of 2700 Oe and above could be obtained in CoCrPt films with Pt contents < 20 at.%; in CoCrPtTa for Pt contents < 12% Pt (with 2.5–5% Ta) and in CoCrPtB (with 3–7% B) for Pt contents < 11%. Also methods for improvement of S∗, noise characteristics and refinement of grain size and surface roughness have been demonstrated.

Analysis of the electronic properties of CoCrPt thin films using parallel electron energy loss spectroscopy (PEELS)

The effects of the Pt content in CoCrPt thin films on the appearance of the near‐edge structure of the Cr and Co L2,3 absorption edges were studied using parallel electron energy loss spectroscopy (PEELS). These reflect local changes in the 3d band of the material. It was found that addition of Pt leads to local fluctuations in the 3d band occupancy in CoCrPt films which causes a decrease of the number of 3d electrons per Co atom. An increase of the L3 to L2 white lines intensities ratio on the L2,3 Co edge with Pt content probably indicates an increase of the magnitude of exchange interactions in the CoCrPt thin films.

Advanced multilayer thin films for ultra-high density magnetic recording media

The magnetic and structural properties of three high-coercivity, low moment multilayers for ultra-high density magnetic recording media were examined. The CoCrPt/Cr/CoCrPt multilayer exhibited extremely small grain size (/spl sim/80 /spl Aring/) and high in-plane coercivity of 3700 Oe. The Cr interlayer caused decoupling of the magnetic layers which led to low S* and low medium noise. The CoCrPt/CoCrPt/CoCrPt multilayer with different amount of intergranular coupling within sublayers exhibited high coercivity /spl sim/2700 Oe and S*=0.90. CoCrPt/CoCrTa multilayer exhibited improved in-plane anisotropy due to larger amount of in-plane oriented c-axes. This led to high coercivity /spl sim/3700 Oe and S*=0.88. Also fine grain diameters were observed in this film. Results obtained suggest that it is possible to produce CoCrPt-based multilayers with properties and structure required for 10 Gbit/inch/sup 2/ longitudinal thin film magnetic recording media. >

Intergranular interactions and structure of multilayer CoCrPt/CoCrTa thin films for ultra-high density recording

Abstract Multilayer CoCrPt/CoCrTa magnetic films with Cr underlayers were studied. The films were fine-grain with in-plane c -axis orientation, the in-plane coercivities H c‖ in the range of 1.9–3.8 kOe and coercivity squareness S ∗ > 0.81 . The H c‖ decreased and S ∗ increased with increasing volume fraction of the CoCrTa layer and intergranular interactions varied significantly with thickness and number of layers in the film.

Effects of CoCrPt layer thickness on the magnetic and structural properties of CoCrPt/Cr thin films

The effects of CoCrPt layer thickness on the magnetic and structural properties of CoCrPt/Cr thin films have been investigated. The in-plane coercivity increased with decreasing thickness for most of the examined compositions, and reached 3050 Oe for films with 13 at.% Pt. It was also found that a decrease of the CoCrPt film thickness leading to M/sub r//spl delta/ >