JPH0252845B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a magnetic recording element comprising a non-magnetic substrate having a major surface providing a continuous layer of magnetic material having Co and Cr as principal components. (Digital) magnetic recording devices have a transmission head (or write/read head) that magnetizes a small area on a magnetic recording element to record (digital) data and scans the magnetized area to read data. used for To date, the only commercially available devices use longitudinal magnetic recording on the device with the easy axis of magnetization parallel to the major surface of the device. Longitudinal magnetic recording uses an annular head with a core of highly permeable material, with a narrow gap placed across the direction of movement of the magnetic recording element in coupling relationship with the flux. A current pulse applied to a coil wound around the core generates a line of magnetic flux within the core that closes along a path that includes one end of the gap, the magnetic portion near the gap, and the other end of the gap. The flux passing through the magnetic layer in this manner records data under its influence. When the magnetized region on the element moves across the gap when reading data, flux sealing is achieved through the core as a result of the flux line passing through the coil and inducing an electrical signal that displays the embedded information. be done. A disadvantage of this type of longitudinal magnetic recording device is that the device can only handle a limited linear bit density. This limitation arises because the magnetic regions of the magnetic layer are magnetically placed in the longitudinal direction of the element. This longitudinal recording method exhibits a constant maximum demagnetizing field at the bit boundaries as a result of the limited number of junctions that can be stored per linear cm of information track. In principle, perpendicular methods of magnetic recording can be used to achieve linear bit densities considerably higher than those provided by longitudinal magnetic recording. In perpendicular magnetic recording, instead of passing longitudinally through the magnetic layer in the plane of the magnetic layer, producing magnetic domains oriented perpendicular to the surface of the magnetic element, magnetic flux passes across the magnetic layer from top to bottom. do. This recording method exhibits a minimum demagnetizing field at the bit boundaries, resulting in a greater number of vertically oriented junctions per linear cm of magnetic element compared to the number of junctions in longitudinal magnetic recording devices. can be accommodated. As is clear from the above, perpendicular magnetic recording involves greater linear writing density than longitudinal magnetic recording. However, while longitudinal magnetic recording is used commercially on a large scale, perpendicular magnetic recording is still in the experimental stage. However, one of the reasons why perpendicular magnetization has not been used on a commercial scale is that suitable recording materials that can fully realize the advantages of perpendicular magnetic recording are not yet available. IE Transactions on Magnetics, Vol. 17, No. 6,
The paper by Sugita et al., "Co-Cr perpendicular recording media by vacuum deposition", published in November 1981, pp. 3172-74 (1), describes the use of vapor-deposited Co1 _{- xCrx} films for perpendicular magnetic recording. is described. The saturation magnetization (σ _s ) of this kind of film is σ _s 0) at x〓0.25.
decreases significantly as the value of increases. High σ _s values are obtained using low concentrations of Cr. The use of Co—Cr films as perpendicular recording materials requires a high σ _s
In addition to the high coercivity, a high coercive force H _e is required. moreover,
Magnetization must be perpendicular to the substrate plane. These special requirements are only realized when using relatively high concentrations of Cr. This indicates that it is necessary to find the optimum temperature because σ _s has not yet decreased much and the requirement of vertical symmetry is already satisfied. Optimal combinations of parameters of this type have been described in various publications.

Table 1 The object of the invention is to provide a recording medium for perpendicular recording methods with considerably improved properties. This object is achieved by a recording medium of the type mentioned above, characterized in that the layer contains an amount of pt of at least 1 atomic % and at most up to 5 atomic %. Adding a small amount of pt to a Co-Cr alloy, especially a Co-Cr _alloy containing 15-30 at. maintain. The nominal compositions of these alloys are shown below. Co _1-x Cr _x Pt _y (where 0<x<1 and 0.01<y
0.05). Embodiments of the present invention will be described below based on the drawings. 1a and 1b show a side view of a perpendicular recording device with a transfer head 11 and a recording element 14, and a sectional view of the transfer head used in this device. A U-shaped core 1 of a highly magnetically conductive material, for example a nickel-iron alloy consisting of 80 atomic % nickel and 20 atomic % iron, is deposited in a thin layer on a substrate 2 by molecular vapor deposition techniques, eg sputtering. establish. The core 1 has a transmission rim 3 and a flux return rim 4 which are interconnected via an intermediate core part 5. As shown in Figure 1b, the transmission rim 3
In the region of the core 1, the layer thickness is d ₁ , and in the region of the flux return rim 4 it is d ₂ , d ₂ > d ₁ , and the width of the end of the transmission rim 3 is W ₁ . ,
The width of the end of the flux return rim 4 is _W2 . The cross-sectional area of the end of the rim 3 (which determines the achievable bit density per unit surface area) is therefore
W ₁ d ₁ and the cross-sectional area of the rim 4 is W ₂ d ₂ . A coil 6 is provided around the transmission rim 3. Since the rim 4 does not write when energizing the coil 6, W ₂ d ₂
must be significantly larger than W ₁ d ₁ , preferably at least 5 to 10 times larger. When the recording element 14 moves perpendicular to the plane of the paper with a speed v, as _shown in FIG. do. Then the transmission rim 3 which is 2-20μm
The width dimension _W1 determines the width of the track written on the recording element. During operation, the core 1 is for example at a height h above the moving magnetic recording element 14. In the case of so-called in-contact recording, h is zero.
The magnetic recording element 14 is a magnetic disk or tape having a non-magnetic substrate 8 providing a magnetic layer 7 with perpendicular magnetic anisotropy. When applying data code current to coil 6 (10
winding coil), a closed circuit for the magnetic flux is generated in the rim 3, the core part 5, the rim 4, the air gap S ₁ with a large cross-sectional area, the magnetic layer 7, the return path 8, the real recording. The resulting magnetic layer 7 facing the rim 3 returns to the rim 3 via an air gap S ₂ of small cross-section. Reversing the current polarity in the desired manner will cause the magnetic layer 7 to
forming regions with perpendicular opposing magnetizations. The distance between the transmission rim 3 and the flux return rim 4 is such that the distance between the rim 3 and the flux return rim 4 is such that the distance between the rim 3 and the flux return rim 4 is
This is a distance that sufficiently prevents the flux from crossing. Furthermore, the distance S provides space for accommodating the coil 6, for example around the transmission rim 3. In order to be able to use perpendicular magnetic recording optimally, the dimension W ₁ is preferably 2 to 20 μm, in which case a dimension of 5 μm is the characteristic value, while the dimension d ₁ is preferably 0.1 to 1 μm, in this case 0.2 μm The dimensions are the characteristic values. FIG. 2 shows the write field H measured in the x direction (which is connected to the coil 6 via the connecting wires 9, 10
(generated by the head 11 when energizing the head 11). In the region R ₁ corresponding to the position of the transmission rim 3 the writing field is very high, but in the region R ₂ corresponding to the position of the flux screen return rim 4
At , the write field is much lower than the non-write position. Since writing fields with acute angles have strong idiosyncrasies and may cause mistaken writing, the corner 1 of the flux return rim 4 is
Make 2 and 13 even more round. The readout information by the readout operation will average out if the "capture" cross-section of the flux return limb 4 is large and will not contribute any usefully to the signal read out by the transmission limb 3. According to the invention, the magnetic layer 7 comprises a Co--Cr alloy with the addition of a small amount of pt. The thickness of this layer is approximately
It is 500nm. In the research paper (2) described by Maeda et al.
It has been demonstrated that in addition to the hexagonal phase, a tetragonal (hcp) phase can be formed in deposited Co--Cr films. The simultaneous nucleation and growth of hcp phase and tetragonal phase microcrystals is troublesome because the hcp phase crystals produce a microstructure with a growth direction with axis C perpendicular to the substrate surface. This troublesome tetragonal phase can be suppressed by using a low substrate temperature (130-150°C). Correct adjustment of such low substrate temperatures is rather difficult, since heating of the substrate always occurs during deposition. As described by Maeda et al.2, this kind of low substrate temperature sacrifices the desired hcp phase to the above-mentioned phases.
with the risk of fcc phase formation. The presence of the fcc phase is extremely troublesome as it leads to a growth direction [101] perpendicular to the substrate, which causes the perpendicular magnetic easy axis of the hcp phase to be lost. The invention is based on the fact that the rate of nucleation and growth is significantly influenced by the addition of Pt. In particular, we succeeded in adding 1% or more of Pt to suppress the formation of the fcc phase in the tetragonal phase. According to studies of metal films by X-ray irradiation, the orientation of the microcrystals corresponds to the direction in which the hexagonal C-axis is perpendicular to the substrate. Surprisingly, the saturation magnetization increases significantly (2% Pt
increase to over 100% by simply adding FIG. 3 shows an example of the results of magnetic measurement. Further, the results are shown in Table 2.

[Table] For comparison, the following values: σ _s −4gmT; H _C ⊥=23kA/m; H _C* ‖=
Co _1-x Cr _x Pt _y alloy showing 28kA/m (x=0.25 and y=
0.01) is used. FIG. 3 shows the hysteresis loop of a 500 nm thick layer of CCo _0.78 Cr _0.22 Pt _0.02 deposited on a non-magnetic carrier of polyester synthetic resin. The value of the perpendicular remanence σ _R ⊥ considerably exceeds the value of the parallel remanence σ _R ‖, which makes the alloy in question extremely well suited for perpendicular recording methods. If the layer contains less than 1 atomic % Pt, σ _R ⊥ becomes σ _R ‖
not greater than The method for manufacturing the layer is shown below. Co, Cr and metals
A vapor mixture of Pt was deposited onto a quartz substrate placed in an ultra-high vacuum bell. A vapor mixture is obtained by each of the three electron beam evaporators, the evaporation rate of which can be independently controlled by a quartz crystal oscillator. The substrate temperature is approximately 250°C. The geometry of the three sources (evaporators) is characterized by an equilateral triangle with a source at each corner. The substrate lies vertically above the center of the triangle approximately 30 cm from the source. The angle of incidence of the vapor flux with respect to the normal on the substrate surface is approximately 15 degrees. Deposition speed is 10~20A/
Changes in seconds. The base pressure of ultra-high vacuum system for vapor deposition is better than 1.3×10 ^-8 Pa (1.3×10 ^-13 Kgf/cm ² ),
During the deposition, the pressure was 1×10 ⁻⁶ Pa (1×10 ⁻¹¹ Kgf/cm ² ). The above method is very suitable for experimental scale experiments when changing the composition of the deposited layer. However, for factory-scale production, if a fixed composition is determined, a single source of alloy of the desired composition may be used. In addition to vapor deposition, sputtering can be used to provide the magnetic layer on the substrate.

[Brief explanation of drawings]

FIG. 1a is a side view of a vertical data storage device having a recording element and a transmission head, FIG. 1b is a sectional view taken along line bb of the transmission head of FIG. 1a, and FIG. 2 is a side view of the transmission head of FIG. 1. Fig. 3 is a graph showing the magnetic field H along the X axis when energized.
It is a graph showing an H loop. 1...core, 2...substrate, 3...transmission rim, 4
...Flux return rim, 5...Core part,
6... Coil, 7... Magnetic layer, 8... Non-magnetic substrate or return path, 9, 10... Connection wire, 11
...Head, 12, 13...Corner, 14...
recording element.

Claims (1)

[Scope of Claims] 1. Magnetic recording comprising a non-magnetic substrate provided with a continuous layer of magnetic material having Co and Cr as main components, the main surface of which exhibits magnetic anisotropy transverse to the main surface. A magnetic recording element, characterized in that the magnetic material further contains Pt in an amount of 1 atomic % or more, and at most 5 atomic %. 2. The magnetic recording element according to claim 1, wherein the layer contains 15 to 30 atom % of Cr.