CA1218568A - Magnetic recording element - Google Patents
Magnetic recording elementInfo
- Publication number
- CA1218568A CA1218568A CA000431050A CA431050A CA1218568A CA 1218568 A CA1218568 A CA 1218568A CA 000431050 A CA000431050 A CA 000431050A CA 431050 A CA431050 A CA 431050A CA 1218568 A CA1218568 A CA 1218568A
- Authority
- CA
- Canada
- Prior art keywords
- magnetic
- limb
- recording
- layer
- magnetic recording
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
- 230000005291 magnetic effect Effects 0.000 title claims abstract description 47
- 239000000758 substrate Substances 0.000 claims abstract description 16
- 229910052804 chromium Inorganic materials 0.000 claims abstract description 5
- 239000000470 constituent Substances 0.000 claims abstract description 3
- 239000000696 magnetic material Substances 0.000 claims description 3
- 230000005415 magnetization Effects 0.000 abstract description 9
- 239000000463 material Substances 0.000 abstract description 5
- 230000004907 flux Effects 0.000 description 15
- 230000002463 transducing effect Effects 0.000 description 14
- 238000000151 deposition Methods 0.000 description 7
- 230000008021 deposition Effects 0.000 description 6
- 238000000034 method Methods 0.000 description 6
- 239000000203 mixture Substances 0.000 description 6
- 229910045601 alloy Inorganic materials 0.000 description 4
- 239000000956 alloy Substances 0.000 description 4
- RKTYLMNFRDHKIL-UHFFFAOYSA-N copper;5,10,15,20-tetraphenylporphyrin-22,24-diide Chemical compound [Cu+2].C1=CC(C(=C2C=CC([N-]2)=C(C=2C=CC=CC=2)C=2C=CC(N=2)=C(C=2C=CC=CC=2)C2=CC=C3[N-]2)C=2C=CC=CC=2)=NC1=C3C1=CC=CC=C1 RKTYLMNFRDHKIL-UHFFFAOYSA-N 0.000 description 4
- 229910000599 Cr alloy Inorganic materials 0.000 description 3
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 2
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- 229910052751 metal Inorganic materials 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- 230000006911 nucleation Effects 0.000 description 2
- 238000010899 nucleation Methods 0.000 description 2
- 229910052697 platinum Inorganic materials 0.000 description 2
- 239000010453 quartz Substances 0.000 description 2
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicon dioxide Inorganic materials O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 2
- 229910001030 Iron–nickel alloy Inorganic materials 0.000 description 1
- 229910001260 Pt alloy Inorganic materials 0.000 description 1
- 230000001154 acute effect Effects 0.000 description 1
- 230000008878 coupling Effects 0.000 description 1
- 238000010168 coupling process Methods 0.000 description 1
- 238000005859 coupling reaction Methods 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 238000013500 data storage Methods 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 230000005347 demagnetization Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000010894 electron beam technology Methods 0.000 description 1
- 230000008020 evaporation Effects 0.000 description 1
- 238000001704 evaporation Methods 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 238000011835 investigation Methods 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- 230000005381 magnetic domain Effects 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 229910052759 nickel Inorganic materials 0.000 description 1
- 238000012856 packing Methods 0.000 description 1
- 230000005855 radiation Effects 0.000 description 1
- 238000004544 sputter deposition Methods 0.000 description 1
- 229920003002 synthetic resin Polymers 0.000 description 1
- 239000000057 synthetic resin Substances 0.000 description 1
- 238000001771 vacuum deposition Methods 0.000 description 1
Classifications
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
- G11B5/62—Record carriers characterised by the selection of the material
- G11B5/64—Record carriers characterised by the selection of the material comprising only the magnetic material without bonding agent
- G11B5/65—Record carriers characterised by the selection of the material comprising only the magnetic material without bonding agent characterised by its composition
- G11B5/656—Record carriers characterised by the selection of the material comprising only the magnetic material without bonding agent characterised by its composition containing Co
Landscapes
- Magnetic Record Carriers (AREA)
- Thin Magnetic Films (AREA)
Abstract
ABSTRACT:
Magnetic recording element of the perpendicular magnetization type having a non-magnetic substrate having a major surface which bears a continuous layer of a mag-netisable material having Co and Cr as main constituents.
This layer also comprises Pt in a quantity of more than 1 at. % up to at most 5 at.%.
Magnetic recording element of the perpendicular magnetization type having a non-magnetic substrate having a major surface which bears a continuous layer of a mag-netisable material having Co and Cr as main constituents.
This layer also comprises Pt in a quantity of more than 1 at. % up to at most 5 at.%.
Description
~2~8568 PII~ 10.3~S 1 22.2.-19~3 ~lagnetic recording element.
The invention relates to a magnetic recording element comprising a non-magnetic substrate having a major surface which bears a continuous layer of a magnetic material having Co and Cr as the main constituents.
(Digital) magnetic recording systems are used in which a transducing head (or write/read head) magnetizes small areas on a magnetic recording element so as to record (digital) data and scans the magnetized areas to read the data. The only commercially useful system so far uses 10 longitudinal magnetic recording on an element having an easy axis of magnetization parallel to a major surface of the element. In longitudinal magnetic recording a head is used of the annular type which comprises a core of a magnetically highl~ permeable material which is provided 15 with a narro~ gap and is placed with the gap transversely to the direction of movement of the magnetic recording element in a flux~coupling relationship therewith. A current pulse applied to a coil wound on the core generates lines of magnetic flu~ in the core which close along a p*h which 20 comprises one edge of the gap, the part of the magnetic adjoining the gap, and the other edge of the gap. The flux pass-ng through the magnetic layer in this manner has for its effect that data are recorded. Upon reading the data when the magnetized area on the element mo~es past the gap, 25 a closing of the flux through the core is realized as a result of which flux lines pass through the coil and induce an electric signal which is representative of the stored information.
The disadvantage of such Longitudinal magnetic 30 recording systems is that the element can handle only a restricted linear bit densi-ty. This restriction occurs because the magnetized areas in the magnetic layer are i~:
Pl-IN 10.388 i2 18 56 8 22.2.1983 magnetically oriented in the longitudinal direction of the element. This longitudinal recording method shows a certain maximum demagnetization field at the bit boundary as a result of which the number of junctions which can be stored per linear centimetre of the information track is restric-ted.
In order to achieve a considerably higher linear bit density than that which is provided by longitu-dinal magnetic recording, the perpendicular manner of magne-tic recording may in principle be used. In perpendicularmagnetic recording the magnetic flux travels transversely through the magnetic layer from the top to the bottom instead of longitudinally through the magnetic layer in the plane of the magnetic layer so as to create magnetic domains 5 which are oriented perpendicularly to the sur~ace o~ the magnetic element, This method of recording shows a minimum demagnetizing field at the bit boundary so that a larger number of perpendicularly oriented junctions per linear centimetre of the magnetic element can be accommodated as 20 compared with the number of junctions in longitudinal magne-tic recording systems.
It will be obvious ~rom the above that perpen-dicular magnetic recording invoives a larger linear packing density than longitudinal magnetic recording. However, 25 longitudinal magnetic recording is used commercially on a large scale, whereas perpendicular magnetic recording is still in the state of examination. One of the reasons why perpendicular magnetization has not been used on a commercial scale yet is that no suitable recording material 30 is yet available with which the advantages of perpendicular magnetic recording can be fully realised.
In the article "Co-Cr perpendicular recording medium by vacuum deposition" by R. Sugita et a~ published in IEE Transactions on Magnetics, Vol. Mag-17, No. 6, 35 November, 1981, ~ 3172-74 (1), the use of vapour-depo~ited C1 xCrx films is described for perpendicular magnetic recording. The saturation magnetization (~s) of such films ,. .
P~IN 10.388 3 1218568 22.2.1983 decreases very strongly ~ith increasing values of x (0 - 0 at x ~ 0.25). High ~ values can be obtained by using low Cr concentrations. For use of Co-Cr films as perpendicular recording materials, a high coercive force IIe is required in addition to a high a ~ Moreover, the magnetization should be perpendicular to the plane of the substrate. These extra requirements can only be realized ~hen using comparatively high Cr concentrations. This means that an optimum concentration has to be found for which a lO has not yet decreased too much and in which~ ho~ever~ the perpendicular symmetry requirement has already been satisIie~1 Such optimurn cornbinations of parameters have been deseribed in lite~ature in various places:
1 5 T~L~ I:
L~el`. ~s (emu/cm3) ~R(emu/cm ) HC(kA/m) . ~ .... . .
Sugital et al. (1) 280 60 56 20 Maeda et al (2) 210 24 24-32 Kobayshi et al.(3) 317 100 80 . ..
(Note: aR represents the remanence measured on a direction perpendicular to the film).
25 See Y. Maeda et al~ Japanese Journal of Applied Physics, 20, 1981,p.L467-L469(2) and K. Kobayashi et al, Journal of Applied Physics, 52, ~arch, 1981, ~, 2453-55 (3).
It is the object of the invention to provide a recording medium for the perpendicular rec~rding method 30 having considerably improved properties.
This object is achi~ed by a recording medium o~ the kind described in the opening paragraph which is characterized in that the layer also comprises Pt in a quantity of more than 1 at. ~0 up to at most 5 at. /0.
The addition of the said small quantity of Pt to Co-Cr alloys, in particular to Co-Cr alloys comprising 15 to 30 at.% of Cr, has been found to result in an increase PIIN 10.388 4 lZ185~8 22,2.1983 of the saturation magnetization ~ by more than 100%
while maintaining the perpendicular anisotropy and the high value of the coercive force. The nominal composition of these alloys may be expressed by the formula Co1 x Crx Pty, in which o~ x ~1 and 0.01< y~ 0.05.
~ n embodiment of the invention ~ill now be described with reference to the accompanying drawing, in which ;
F~re 1a is a side elevation of a data storage device of the vertical type having a recording element and a transducing head, Figure 1b is a sectional view of the transduci~g head of Figure 1a taken on the line Ib-Ib.
~ igure 2 is a graph showing the field ~I
along the X axis upon energizing the transducing head of Figure 1, and Figure 3 is a graph showing the ~-I-I loop of a Co-Cr-Pt alloy in the first two quadrants Figures 1a and 1b are a side elevation of a device for perpendicular recording with a transducing head 11 and a recording element 14 and a cross-sectional view, respectively, of the transducing head used in this device, A U-shaped core 1 of a highly magnetically permeable material, for example a nickel-iron alloy consisting of 80 at.~O nickel and 20 at.% iron~ is provided in the form of a thin layer on a substra-te 2 by means of a molecular deposi-tion technique, for example spwttering, The core 1 comprises a transducing limb 3 and a flux return limb 4 which are interconnected via an intermediate core part 5, As shown in ~igure lb, the layer thickness of core 1 at the area of the transducing limb 3 is d1 and at the area of the flux return limb 4 it is d2, where d2 > d1~ while the end of the transducing limb 3 has a width W1 and the end of the flux return limb 4 has a width W2, The area of the cross-section of the end of limb 3 (which determines the achievable bit density per unit of surface area) thus is W1 d1 and the area of the cross-section of the limb 4 thus is W2 d2. A
P~-IN 10.388 ~218568 22.2.1983 coil 6 is provided around transducing limb 3. In order that the limb 4 does not write when coil 6 is energized, l~2 d2 must be considerably larger than W1 d1, preferably at least 5 to 10 times as large. When the recording element 14 moves perpendicularly to the plane of the paper at a velocity UY, as shown in Figure 1a~ the thiclcness dimension d1 of the end of the transducing limb 3 which may be between O.1 and 1/um determines the number of flu~ junctions per linear centimetre. The width dimension W1 of the transducing limb 3 which may be between 2 and 20/um thcn determines the width of the track which is wri-tten on the recording elernent. ~uring operation the core 1 is, for exarnple, at a height h above the moving m~gnetic element 14 In -the case of so-called in-contact recording, h Inay be zero. rhe magnetic element 14 may be a magnetic disc or tape having a non-magnetic substrate 8 which bears a magnetic layer 7 having a perpendicular magnetic aniso-tropy.
When a data-coded current is applied to the coil 6 (a coil having ten turns is shown) a closed path for the magnetic flux is generated in limb 3~ intermediate core part 5, limb 4, an airgap S1 having the larger cross-.section, the magnetic layer 7, the return path 8, the magnetic layer 7 opposite to limb 3 where the actual recording is produced, an air gap S2 having the smaller cross-section and back to limb 3.
By reversing the polarity of the current in a desired manner domains are thus formed having perpendicu-lar opposite magnetizations in the magnetic layer 7.
The distance S between the t-ansducing limb 3 and the flux return limb 4 is sufficien-t to prevent flux during the writing process from crossing directly from limb 3 to limb 4. ~oreover, the distance S is such as to provide space to accommodate the coil 6 around the trans-ducing limb 3.
In order to be able to use the perpendicularmagnetic recording optimally, the dimension W1 should 121856~3 P~IN 10.388 6 22.2.1983 preferably be between 2 and 20/um, a dime~sion of 5/um being a characteristic value in this case, while the dimension d1 preferably is between 0.1 and 1/um~ a dimension o~ 0.2/um being a characteristic value in this case.
Figure 2 showsthe writing field H (the field which is generated by the head 11 upon energizing the coil 6 via the connection wires 9, 10), measured in the x-direction. In the area R1 which corresponds to the locatian of the transducing limb 3, the writing field is very high, while in the area R2 which corresponds to the location of the flux return limb 5 the field is so much lower that there is no writing. Because with acute angles a strong singularity in the writing field occurs which accidentally may lead to writing~ the corners 12, 13 of flux return limb 4 are moreover rounded off. With reading opera-tions any read information will average as a result of the large "capture" cross-section of the flux return limb 4 and will not give any effective contribution to the signal read by transducing limb 3.
According to the invention the magnetic layer 7 comprises a Co-Cr alloy to which a certain small quantity of Pt has been added, The layer has a thlckness of approxi-mately 500 nm.
In the investigation described by Maeda (2) it was demonstrated that in vapour-deposited Co-Cr films a tetragonal phase may be formed in addition to the hexagonal (hcP) phase The simultaneous nucleation and growth of hcp and tetragonal crystallites is annoying for producing a 30 microstructure in which the crystallites of the _~ phase have a direction of growth with their c axis perpendicular to the substrate surface. The annoying tetragonal phase can be suppressed by using low substrate temperatures (130 -150 C). Due to the fact that heating of the substrate always occurs during vapour deposition, a correct adjust-ment of such low substrate temperatures is rather difficult.
As described by Maeda et al (2), such low substrate tempe-PII~ 10.3~8 7 22.2.1983 ratures involve the risk of the formation of' an fccphase in ad~ition to the above-described phases at the expense of the desired hcp phase. The presence of said fcc phase is extremely annoying because a direction of growth r101~ perpendicular to the substrate is introduced hereby as a result of ~hich of course the perpendicular eas~ axis of magnetization of the hcp phase is lost.
The present invention is based on the fact that the velocities oI' nucleation and growth can be considerably influence~ by the addition of Pt, It has succeeded in particular by the addition of rnore than 1/J Pt to suppress the formation of` the tetra-gonal and fcc phases. According to an in~estigation of the metal films by means of X-ray radiation~ the orientation of ;5 thc crystallites corresponds to a direction in which their hexagonaL c-axis is perpendicular to the substrate plane. A
surpri6ing result is the enormous increase of the saturation magnetization (by more than 100% when only 2% Pt is a~de~).
Figure 3 shows an example of the result of 20 magnetic measurements. Further results are recorded in Table II, TABLE II
C1-xCrx Pty ~s(mT) HCl kA/m Hcll kA/m .. . .
25 x=0.25 Y=0.05 52 88 56 0.23 0. 05 88 120 48 0.25 0.03 88 100 L~8 0.22 0.03 105 72 40 0.2 8 0 ' 3 72 64 32 30 0.18 0.03 75 80 40 0.22 0. 02 52 80 40 0.18 0.02 68 72 28 , . . .
For comparison may ser~e that a C1 x Crx Pty alloy with x = 0.25 and y = 0.01 presented the following ~alues :
i~ - 4 ~mT ; H l = 28 kA/m ; H il = 28 lcA/m PHN 10.388 8 22.2.1983 Figure 3 sho~s the hysteresis loop at room temperature of a 500 nm thick CoO 78CrO 22Pto 02 layer vapour-deposited on a non-magnetic carrier of a p~yester synthetic resin. The value of the perpendicular remanence 5 OR lexceeds significantly the value of the parallel remanence ~ Il, which makes the alloy in question extremely suitable for the perpendicular recording method.
1~hen the layer comprises less than 1 at./0 Pt, ~R l is not larger than ~ Il.
The layer was manufactured as follows. A vapour mixture of the metals Co, Cr and Pt was deposited on a quartz substrate placed in a ultra high vacuum bell. The vapour mixture was obtained by three individual electron beam evaporators the evaporation rates of which could be control-5 led independently by means of quartz crystal oscillators.
The substrate temperature was approximately 250C. The geometric arrangement of the three sources (evaporators) can be characterized by means of an equilateral triangle having a source at each of the corners. The substrate is present 20vertically above the centre of the triangle approximately 30 cms from the sources. The angle of incidence of the vapour flux with respect to the normal to the substrate surface is approximately 15 dggrees. The vapour deposition rates varied between 10 and 20 A / sec. The base pressure in the Ultra-25high vacuum system for vapour deposition was better than 1.3x10 8 Pa and during the vapour deposition 1x10 6 Pa.
The above-described method is excellently suitable for experiments on a laboratory scale when the composition of the vapour-deposited layers is to be varied.
30However, for production on a factory scale it is better, when a certain composition has been decided, to use a single vapour deposition source which consists of an alloy of the desired composition. In addition to vapour deposition, sputtering may be used to provide the magnetic layer on a 35substrate.
The invention relates to a magnetic recording element comprising a non-magnetic substrate having a major surface which bears a continuous layer of a magnetic material having Co and Cr as the main constituents.
(Digital) magnetic recording systems are used in which a transducing head (or write/read head) magnetizes small areas on a magnetic recording element so as to record (digital) data and scans the magnetized areas to read the data. The only commercially useful system so far uses 10 longitudinal magnetic recording on an element having an easy axis of magnetization parallel to a major surface of the element. In longitudinal magnetic recording a head is used of the annular type which comprises a core of a magnetically highl~ permeable material which is provided 15 with a narro~ gap and is placed with the gap transversely to the direction of movement of the magnetic recording element in a flux~coupling relationship therewith. A current pulse applied to a coil wound on the core generates lines of magnetic flu~ in the core which close along a p*h which 20 comprises one edge of the gap, the part of the magnetic adjoining the gap, and the other edge of the gap. The flux pass-ng through the magnetic layer in this manner has for its effect that data are recorded. Upon reading the data when the magnetized area on the element mo~es past the gap, 25 a closing of the flux through the core is realized as a result of which flux lines pass through the coil and induce an electric signal which is representative of the stored information.
The disadvantage of such Longitudinal magnetic 30 recording systems is that the element can handle only a restricted linear bit densi-ty. This restriction occurs because the magnetized areas in the magnetic layer are i~:
Pl-IN 10.388 i2 18 56 8 22.2.1983 magnetically oriented in the longitudinal direction of the element. This longitudinal recording method shows a certain maximum demagnetization field at the bit boundary as a result of which the number of junctions which can be stored per linear centimetre of the information track is restric-ted.
In order to achieve a considerably higher linear bit density than that which is provided by longitu-dinal magnetic recording, the perpendicular manner of magne-tic recording may in principle be used. In perpendicularmagnetic recording the magnetic flux travels transversely through the magnetic layer from the top to the bottom instead of longitudinally through the magnetic layer in the plane of the magnetic layer so as to create magnetic domains 5 which are oriented perpendicularly to the sur~ace o~ the magnetic element, This method of recording shows a minimum demagnetizing field at the bit boundary so that a larger number of perpendicularly oriented junctions per linear centimetre of the magnetic element can be accommodated as 20 compared with the number of junctions in longitudinal magne-tic recording systems.
It will be obvious ~rom the above that perpen-dicular magnetic recording invoives a larger linear packing density than longitudinal magnetic recording. However, 25 longitudinal magnetic recording is used commercially on a large scale, whereas perpendicular magnetic recording is still in the state of examination. One of the reasons why perpendicular magnetization has not been used on a commercial scale yet is that no suitable recording material 30 is yet available with which the advantages of perpendicular magnetic recording can be fully realised.
In the article "Co-Cr perpendicular recording medium by vacuum deposition" by R. Sugita et a~ published in IEE Transactions on Magnetics, Vol. Mag-17, No. 6, 35 November, 1981, ~ 3172-74 (1), the use of vapour-depo~ited C1 xCrx films is described for perpendicular magnetic recording. The saturation magnetization (~s) of such films ,. .
P~IN 10.388 3 1218568 22.2.1983 decreases very strongly ~ith increasing values of x (0 - 0 at x ~ 0.25). High ~ values can be obtained by using low Cr concentrations. For use of Co-Cr films as perpendicular recording materials, a high coercive force IIe is required in addition to a high a ~ Moreover, the magnetization should be perpendicular to the plane of the substrate. These extra requirements can only be realized ~hen using comparatively high Cr concentrations. This means that an optimum concentration has to be found for which a lO has not yet decreased too much and in which~ ho~ever~ the perpendicular symmetry requirement has already been satisIie~1 Such optimurn cornbinations of parameters have been deseribed in lite~ature in various places:
1 5 T~L~ I:
L~el`. ~s (emu/cm3) ~R(emu/cm ) HC(kA/m) . ~ .... . .
Sugital et al. (1) 280 60 56 20 Maeda et al (2) 210 24 24-32 Kobayshi et al.(3) 317 100 80 . ..
(Note: aR represents the remanence measured on a direction perpendicular to the film).
25 See Y. Maeda et al~ Japanese Journal of Applied Physics, 20, 1981,p.L467-L469(2) and K. Kobayashi et al, Journal of Applied Physics, 52, ~arch, 1981, ~, 2453-55 (3).
It is the object of the invention to provide a recording medium for the perpendicular rec~rding method 30 having considerably improved properties.
This object is achi~ed by a recording medium o~ the kind described in the opening paragraph which is characterized in that the layer also comprises Pt in a quantity of more than 1 at. ~0 up to at most 5 at. /0.
The addition of the said small quantity of Pt to Co-Cr alloys, in particular to Co-Cr alloys comprising 15 to 30 at.% of Cr, has been found to result in an increase PIIN 10.388 4 lZ185~8 22,2.1983 of the saturation magnetization ~ by more than 100%
while maintaining the perpendicular anisotropy and the high value of the coercive force. The nominal composition of these alloys may be expressed by the formula Co1 x Crx Pty, in which o~ x ~1 and 0.01< y~ 0.05.
~ n embodiment of the invention ~ill now be described with reference to the accompanying drawing, in which ;
F~re 1a is a side elevation of a data storage device of the vertical type having a recording element and a transducing head, Figure 1b is a sectional view of the transduci~g head of Figure 1a taken on the line Ib-Ib.
~ igure 2 is a graph showing the field ~I
along the X axis upon energizing the transducing head of Figure 1, and Figure 3 is a graph showing the ~-I-I loop of a Co-Cr-Pt alloy in the first two quadrants Figures 1a and 1b are a side elevation of a device for perpendicular recording with a transducing head 11 and a recording element 14 and a cross-sectional view, respectively, of the transducing head used in this device, A U-shaped core 1 of a highly magnetically permeable material, for example a nickel-iron alloy consisting of 80 at.~O nickel and 20 at.% iron~ is provided in the form of a thin layer on a substra-te 2 by means of a molecular deposi-tion technique, for example spwttering, The core 1 comprises a transducing limb 3 and a flux return limb 4 which are interconnected via an intermediate core part 5, As shown in ~igure lb, the layer thickness of core 1 at the area of the transducing limb 3 is d1 and at the area of the flux return limb 4 it is d2, where d2 > d1~ while the end of the transducing limb 3 has a width W1 and the end of the flux return limb 4 has a width W2, The area of the cross-section of the end of limb 3 (which determines the achievable bit density per unit of surface area) thus is W1 d1 and the area of the cross-section of the limb 4 thus is W2 d2. A
P~-IN 10.388 ~218568 22.2.1983 coil 6 is provided around transducing limb 3. In order that the limb 4 does not write when coil 6 is energized, l~2 d2 must be considerably larger than W1 d1, preferably at least 5 to 10 times as large. When the recording element 14 moves perpendicularly to the plane of the paper at a velocity UY, as shown in Figure 1a~ the thiclcness dimension d1 of the end of the transducing limb 3 which may be between O.1 and 1/um determines the number of flu~ junctions per linear centimetre. The width dimension W1 of the transducing limb 3 which may be between 2 and 20/um thcn determines the width of the track which is wri-tten on the recording elernent. ~uring operation the core 1 is, for exarnple, at a height h above the moving m~gnetic element 14 In -the case of so-called in-contact recording, h Inay be zero. rhe magnetic element 14 may be a magnetic disc or tape having a non-magnetic substrate 8 which bears a magnetic layer 7 having a perpendicular magnetic aniso-tropy.
When a data-coded current is applied to the coil 6 (a coil having ten turns is shown) a closed path for the magnetic flux is generated in limb 3~ intermediate core part 5, limb 4, an airgap S1 having the larger cross-.section, the magnetic layer 7, the return path 8, the magnetic layer 7 opposite to limb 3 where the actual recording is produced, an air gap S2 having the smaller cross-section and back to limb 3.
By reversing the polarity of the current in a desired manner domains are thus formed having perpendicu-lar opposite magnetizations in the magnetic layer 7.
The distance S between the t-ansducing limb 3 and the flux return limb 4 is sufficien-t to prevent flux during the writing process from crossing directly from limb 3 to limb 4. ~oreover, the distance S is such as to provide space to accommodate the coil 6 around the trans-ducing limb 3.
In order to be able to use the perpendicularmagnetic recording optimally, the dimension W1 should 121856~3 P~IN 10.388 6 22.2.1983 preferably be between 2 and 20/um, a dime~sion of 5/um being a characteristic value in this case, while the dimension d1 preferably is between 0.1 and 1/um~ a dimension o~ 0.2/um being a characteristic value in this case.
Figure 2 showsthe writing field H (the field which is generated by the head 11 upon energizing the coil 6 via the connection wires 9, 10), measured in the x-direction. In the area R1 which corresponds to the locatian of the transducing limb 3, the writing field is very high, while in the area R2 which corresponds to the location of the flux return limb 5 the field is so much lower that there is no writing. Because with acute angles a strong singularity in the writing field occurs which accidentally may lead to writing~ the corners 12, 13 of flux return limb 4 are moreover rounded off. With reading opera-tions any read information will average as a result of the large "capture" cross-section of the flux return limb 4 and will not give any effective contribution to the signal read by transducing limb 3.
According to the invention the magnetic layer 7 comprises a Co-Cr alloy to which a certain small quantity of Pt has been added, The layer has a thlckness of approxi-mately 500 nm.
In the investigation described by Maeda (2) it was demonstrated that in vapour-deposited Co-Cr films a tetragonal phase may be formed in addition to the hexagonal (hcP) phase The simultaneous nucleation and growth of hcp and tetragonal crystallites is annoying for producing a 30 microstructure in which the crystallites of the _~ phase have a direction of growth with their c axis perpendicular to the substrate surface. The annoying tetragonal phase can be suppressed by using low substrate temperatures (130 -150 C). Due to the fact that heating of the substrate always occurs during vapour deposition, a correct adjust-ment of such low substrate temperatures is rather difficult.
As described by Maeda et al (2), such low substrate tempe-PII~ 10.3~8 7 22.2.1983 ratures involve the risk of the formation of' an fccphase in ad~ition to the above-described phases at the expense of the desired hcp phase. The presence of said fcc phase is extremely annoying because a direction of growth r101~ perpendicular to the substrate is introduced hereby as a result of ~hich of course the perpendicular eas~ axis of magnetization of the hcp phase is lost.
The present invention is based on the fact that the velocities oI' nucleation and growth can be considerably influence~ by the addition of Pt, It has succeeded in particular by the addition of rnore than 1/J Pt to suppress the formation of` the tetra-gonal and fcc phases. According to an in~estigation of the metal films by means of X-ray radiation~ the orientation of ;5 thc crystallites corresponds to a direction in which their hexagonaL c-axis is perpendicular to the substrate plane. A
surpri6ing result is the enormous increase of the saturation magnetization (by more than 100% when only 2% Pt is a~de~).
Figure 3 shows an example of the result of 20 magnetic measurements. Further results are recorded in Table II, TABLE II
C1-xCrx Pty ~s(mT) HCl kA/m Hcll kA/m .. . .
25 x=0.25 Y=0.05 52 88 56 0.23 0. 05 88 120 48 0.25 0.03 88 100 L~8 0.22 0.03 105 72 40 0.2 8 0 ' 3 72 64 32 30 0.18 0.03 75 80 40 0.22 0. 02 52 80 40 0.18 0.02 68 72 28 , . . .
For comparison may ser~e that a C1 x Crx Pty alloy with x = 0.25 and y = 0.01 presented the following ~alues :
i~ - 4 ~mT ; H l = 28 kA/m ; H il = 28 lcA/m PHN 10.388 8 22.2.1983 Figure 3 sho~s the hysteresis loop at room temperature of a 500 nm thick CoO 78CrO 22Pto 02 layer vapour-deposited on a non-magnetic carrier of a p~yester synthetic resin. The value of the perpendicular remanence 5 OR lexceeds significantly the value of the parallel remanence ~ Il, which makes the alloy in question extremely suitable for the perpendicular recording method.
1~hen the layer comprises less than 1 at./0 Pt, ~R l is not larger than ~ Il.
The layer was manufactured as follows. A vapour mixture of the metals Co, Cr and Pt was deposited on a quartz substrate placed in a ultra high vacuum bell. The vapour mixture was obtained by three individual electron beam evaporators the evaporation rates of which could be control-5 led independently by means of quartz crystal oscillators.
The substrate temperature was approximately 250C. The geometric arrangement of the three sources (evaporators) can be characterized by means of an equilateral triangle having a source at each of the corners. The substrate is present 20vertically above the centre of the triangle approximately 30 cms from the sources. The angle of incidence of the vapour flux with respect to the normal to the substrate surface is approximately 15 dggrees. The vapour deposition rates varied between 10 and 20 A / sec. The base pressure in the Ultra-25high vacuum system for vapour deposition was better than 1.3x10 8 Pa and during the vapour deposition 1x10 6 Pa.
The above-described method is excellently suitable for experiments on a laboratory scale when the composition of the vapour-deposited layers is to be varied.
30However, for production on a factory scale it is better, when a certain composition has been decided, to use a single vapour deposition source which consists of an alloy of the desired composition. In addition to vapour deposition, sputtering may be used to provide the magnetic layer on a 35substrate.
Claims (2)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A magnetic recording element comprising a non-magnetic substrate having a major surface which bears a continuous layer of a magnetic material having Co and Cr as main constituents, said layer showing a magnetic aniso-tropy transverse to the major surface, characterized in that the magnetic material also comprises Pt in a quantity of more than 1 at.% up to at most 5 at.%.
2. A recording element as claimed in Claim 1, char-acterized in that the layer comprises 15 to 30 at.% Cr.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| NL8202596 | 1982-06-28 | ||
| NL8202596A NL8202596A (en) | 1982-06-28 | 1982-06-28 | MAGNETIC REGISTRATION MEDIUM. |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1218568A true CA1218568A (en) | 1987-03-03 |
Family
ID=19839941
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000431050A Expired CA1218568A (en) | 1982-06-28 | 1983-06-23 | Magnetic recording element |
Country Status (7)
| Country | Link |
|---|---|
| JP (1) | JPS5911605A (en) |
| AU (1) | AU552637B2 (en) |
| CA (1) | CA1218568A (en) |
| DE (1) | DE3321944A1 (en) |
| FR (1) | FR2529366B1 (en) |
| GB (1) | GB2125069B (en) |
| NL (1) | NL8202596A (en) |
Families Citing this family (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS6150211A (en) * | 1984-08-20 | 1986-03-12 | Res Dev Corp Of Japan | Vertical magnetic recording medium and its production |
| US4678721A (en) * | 1986-04-07 | 1987-07-07 | U.S. Philips Corporation | Magnetic recording medium |
| US4749628A (en) * | 1986-04-29 | 1988-06-07 | International Business Machines Corporation | Multilayered vertical magnetic recording medium |
| JPH0758540B2 (en) * | 1986-06-27 | 1995-06-21 | ホ−ヤ株式会社 | Magnetic recording medium |
| US4789598A (en) * | 1987-01-20 | 1988-12-06 | International Business Machines Corporation | Thin film medium for horizontal magnetic recording having an improved cobalt-based alloy magnetic layer |
| JP2785276B2 (en) * | 1988-07-27 | 1998-08-13 | 三菱化学株式会社 | Magnetic recording media |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4429016A (en) * | 1980-03-07 | 1984-01-31 | Matsushita Electric Industrial Co., Ltd. | Magnetic recording medium with vacuum deposited magnetic layer |
-
1982
- 1982-06-28 NL NL8202596A patent/NL8202596A/en active Search and Examination
-
1983
- 1983-06-18 DE DE19833321944 patent/DE3321944A1/en not_active Withdrawn
- 1983-06-23 CA CA000431050A patent/CA1218568A/en not_active Expired
- 1983-06-24 FR FR8310487A patent/FR2529366B1/en not_active Expired
- 1983-06-24 GB GB08317165A patent/GB2125069B/en not_active Expired
- 1983-06-25 JP JP58114995A patent/JPS5911605A/en active Granted
- 1983-06-27 AU AU16275/83A patent/AU552637B2/en not_active Ceased
Also Published As
| Publication number | Publication date |
|---|---|
| GB2125069B (en) | 1985-10-30 |
| NL8202596A (en) | 1984-01-16 |
| GB2125069A (en) | 1984-02-29 |
| AU552637B2 (en) | 1986-06-12 |
| DE3321944A1 (en) | 1983-12-29 |
| AU1627583A (en) | 1984-01-05 |
| JPH0252845B2 (en) | 1990-11-14 |
| FR2529366A1 (en) | 1983-12-30 |
| FR2529366B1 (en) | 1986-11-14 |
| JPS5911605A (en) | 1984-01-21 |
| GB8317165D0 (en) | 1983-07-27 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US4678721A (en) | Magnetic recording medium | |
| US6834026B2 (en) | Method for thermally-assisted recording on a magnetic recording disk | |
| US6403203B2 (en) | Magnetic recording medium and magnetic recording apparatus using the same | |
| EP1308936A1 (en) | Highly Oriented Magnetic Thin Films, Recording Media, Transducers, Devices Made Therefrom and Methods of Making | |
| JPH0722235A (en) | Thin film and magnetic head of multilayer ferromagnetic material using common material | |
| JPS6231051A (en) | Photomagnetic recording medium | |
| US6395413B1 (en) | Perpendicular magnetic recording medium | |
| CA1315612C (en) | Perpendicular magnetic storage medium | |
| JPS62119760A (en) | magneto-optical recording material | |
| CA1218568A (en) | Magnetic recording element | |
| JPH07503337A (en) | Magnetic recording media using soft magnetic materials | |
| EP1324317B1 (en) | Perpendicular magnetic recording medium and information storing device | |
| JPH03154217A (en) | Magnetic head and magnetic recorder | |
| JPH09501790A (en) | Magneto-optical recording medium | |
| EP0169928A1 (en) | Magnetic recording medium | |
| JPS62134817A (en) | Magnetic recording medium | |
| Lodder | Magnetic thin films for high-density recording | |
| Turilli et al. | Magneto and magneto-optical recording materials | |
| JPS58114329A (en) | Magnetic recording medium | |
| JPS59157834A (en) | Magnetic recording medium | |
| JPH0387005A (en) | Magnetic film | |
| Lairson et al. | Atomically Layered Structures for Perpendicular Magnetic Information Storage | |
| JPH06301904A (en) | High-density recording and reproducing method | |
| JPH0570205B2 (en) | ||
| JPS62267949A (en) | Magneto-optical recording medium |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |