JPS6021516A - Manufacture of iron oxide magnetic thin film - Google Patents

Abstract

PURPOSE:To obtain a gamma-Fe2O3 thin film which is suitably used as a medium for magnetic disc having a high recording density by improving the squareness of hysteresis loop in the magnetizing direction. CONSTITUTION:On the occasion of obtaining a gamma-Fe2O3 thin film by forming an Fe2O3 thin film by heating O2-added alpha-Fe2O3 thin film manufactured by the reactive sputtering method in the flow of hydrogen and consequently heating it in the atmospheric ambient, a sample is magnetized by applying a magnetic field thereto during total process of oxidation under the atmospheric ambient or before or in the course of the oxidation under the atmospheric condition. The coercive force (Hc) and squareness of hysteresis loop of magnetic thin film thus obtained are remarkably improved. In case such thin film is used as a magnetic recording medium, recording density, regenerated output, repeatability and signal to noise ratio can also be improved.

Description

Detailed Description of the Invention (Technical Field) (1) The present invention relates to a method for producing an iron oxide magnetic thin film, and a method for manufacturing a γ-Fe magnetic thin film, which is mainly used as a medium for high recording density magnetic disks.
20. The present invention relates to a method for manufacturing a thin film.

(Prior art wi) Conventionally, in order to increase the density of magnetic recording, efforts have been made to make the media thinner and to increase the coercive force. To that end, the conventionally used γ-Fe20. The γ-
Fe20. Thin films have been developed as magnetic disk media (e.g. J, A, ppl.

Phys,”VOl,,tJ,AJ,/9ffj
, pp, Jj3t~2SAO). This r -y
e2o, which increases the coercive force (Ha) of the thin film,
Conventionally, CO or O8 was added in an amount of only a few atomic percent of metal elements (for example, IEEE' Tra
ns, Nag, 'Vo'1. MAG-/j.

1979, pp, /1119-/33/, or Tokugansho! ;7-/Otsu4Ii, i4! (see issue).

By the way, the maximum value (Hx) of the horizontal component of the recording magnetic field generated by the head wall of a magnetic disk is Karlqivistl
It is calculated as follows according to the formula:

Hx = lr Is cot-'(''/,, )M
Saturation magnetization of S2 head material y: Distance between head and medium g: Head gap length The saturation magnetization (Ms) of ferrite, which is the most commonly used head material, is set to 1100 GaugSN, and the rad gap length is set to 0.3 μm. , when the distance between the medium and the head is 0.2 μm, and the thickness of the medium is o and i μm,
The HX reaching the lower layer of the medium is approximately /s000e.

If the minimum value of the external magnetic field necessary for the hysteresis loop of the medium to become a major roof (for example, Hs in the hysteresis loop shown in Figure 1) is greater than or equal to tsoo Os, the medium will not meet the above recording conditions. In this case, saturation does not occur, resulting in so-called unsaturated recording, resulting in deterioration of overwriting characteristics and erasing characteristics. Conventionally, γ-Fe20. In a thin film, there is a relationship of Hs-αHa (α=/, 1-2.0) (α-Hx/Ha), and in the case of Ha of approximately 000e or more, Hs, 1? /! ;000e,
When the HXO value exceeds the above-mentioned value, it is rejected. That is, even when increasing H to increase recording density,
It is necessary to minimize the increase in HX. 1
Therefore, most ideally, α=/,O.

On the other hand, the quantity S' = Hr /Ha (see Figure 1), which indicates Ill at the coercive force point of the hysteresis loop, is also important and greatly affects the recording density in saturation magnetic recording.

That is, even if the gradient of the write magnetic field from the head is the same, the larger S7 is, the narrower the recording magnetization reversal region width a of the medium becomes, thereby achieving higher recording density. Conventionally, γ-Fe20. thin films of S-0.77 have been put to practical use, to which several atomic percent or less of Ti or O have been added for the purpose of improving S''.

Inversion region width a and medium characteristics (film thickness d, residual magnetization Mr
, coercive force Ha, and S, etc.) is Ta1ks
(IBM J, Res
.

DelVellOp, /? , lr~! ;9 Otsu(
/975)). In addition, the reversal area width a and the recording density D5
0 (recording density at which the output decreases to half the solitary wave output) has also been clarified by 00mBtOOk et al. (IBMJ, Res, DeVf310p,
/I, 316-j6 (see /974/)).

Based on the relational expression they derived, when calculating the dependence of Dso on H or S, when S8 increases by 0./increase, D5o becomes approximately 100 FRPM (Flux Rever
salPer Millimeter) increases and He
Even if increases by 1000e, D5o is approximately 100 FR
It is shown that PM increases. However, this is the film thickness d
is 0072 μm1 residual magnetization Mr ha2 uOGauss,
Head gap length g is 0, /jμm% Head flying height is 0. /μmXHa is 700~10000e SS''
is a calculation within the condition range of o, to -o, and qs. D
,. An improvement in the signal-to-noise ratio means an increase in the reproduction output at high recording density, and it is clear that this results in an improvement in the signal-to-noise ratio if the noise generated from the medium is constant.

(Objective) In view of the above points, an object of the present invention is to provide a method for manufacturing an iron oxide magnetic thin film that can improve the rectangularity of the hysteresis loop in the magnetization direction.

(Structure of the Invention) In order to achieve the above object, the present invention provides O8-doped α-Fe2O, produced using a reactive sputtering method.
The thin film is heated in a hydrogen stream to form a Fe3O4 thin film, and then heated in air to form r -Fe2O.

To obtain a thin film, a magnetic field is applied to the sample during the whole process of atmospheric oxidation, or before or during the process of atmospheric oxidation, so that the sample is magnetized.

(Example) The present invention will be described in detail below with reference to its embodiments.

Example 1 Using a 99.9at%Fe plate as a target, SO
α-Fe205 film was formed by reactive sputtering in a mixed gas atmosphere of %Al" Added.

The sputtering atmosphere pressure is 1×/θ Torr, sputtering (
6) The electric power was 200W. The sputtering method was a DC magnetron method. The substrate was an A alloy disk coated with alumite with a diameter of 2/cIn, and the substrate was rotated at 101"pm during sputtered film formation to keep the film thickness distribution in the circumferential direction of the substrate disk constant. By performing sputtering for 55 minutes, α-Fe20 with a thickness of 0./7 μm was
3 thin films were formed. Here, the amount of O8 added can be adjusted by adjusting the amount of Os powder placed on the target. o, rr in the α-Fe203 thin film formed by sputtering
at,% Os was added in the proportion of only the metal element.

α-Fe20 to which this OB was added. A Fe,04 film was obtained by heating the thin film at a temperature of 2IIO°C for 3 hours in a H2 stream bubbled with 1°C water.

The disk substrate to which this Fe, 04 film is attached is
After cutting into corners, γ-Fe20. A film was formed.

(1) As before, heat at 210°C for 1 hour in the air.

(2) After applying a magnetic field of 11 koe parallel to the film surface of the Fe,04 film, the magnetic field was removed and the Fe,04 film was left with residual magnetization in one direction. Heat for an hour.

(3) Heating in the atmosphere at 1j°C for q hours to form a film in an intermediate oxidation state of Fe3O4 and γ-Fe2O. After applying a magnetic field of Q koe in parallel to the film surface, the magnetic field is removed to create a state of residual magnetization in one direction within the film surface, and then the film is heated again at 2ro° C. for a period of time in the atmosphere.

(4) γ-F by heating rro 'CK in air for 1 hour
After forming the e203 thin film, tlk06 was applied parallel to the film surface.
Apply an external magnetic field of After that, the magnetic field is removed to create a state of residual magnetization in one direction within the film plane, and then the film is exposed to the atmosphere again.
Heat to 2rO<0>C for 1 hour.

(5) While applying an external magnetic field of &kOe parallel to the film surface, the film is heated to 210° C. for 10 minutes in the atmosphere, and then the external magnetic field is removed. Subsequently, the mixture is heated to 2ro° C. in the air for a period of time.

(6) Heat to 210° C. in the atmosphere while applying an external magnetic field of It kOe parallel to the film surface.

The fact that the film after oxidation is a film mainly composed of γ-Fe20S phase can be confirmed by electron beam diffraction of the film formed by heat treatment method (1), which shows (2//), (
ko10).

This can be confirmed by detecting a reflection peak due to the superlattice such as (/10).

r-Fe2 formed by the above four types of heat treatment methods
The results of measuring the magnetic properties of the O thin film are as follows:
Shown in the table.

(9) γ-Fe2o3 thin film r (
Therefore, we applied a measurement magnetic field in an arbitrary direction, but the heat treatment method (
For samples 2) to (6), a measurement magnetic field was applied in the same direction as the magnetic field applied during heat treatment. Heat treatment methods (2) to (6)
), the thin film was prepared using a heat treatment method (
1) γ-Fe20. Compared to the thin film, Ha, α, and s8 were all improved, and it was confirmed that a hysteresis loop with good rectangularity was obtained.

Example 2 Using a λat, %Co, rat, and %Fe alloy plate with a diameter of α as a target, 50%Ar + S0%02
High-frequency sputtering is performed in an ambient atmosphere to form a 0.000. An α-Fe2o5 thin film with a thickness of IQ μm was formed. At this time, a KOs pellet was placed on the target,
r, i at,% and λ,/J at8% were added.

The sputtering atmosphere pressure was IX1O-5 Torr, and the sputtering power was kW/kW. These two types of Os addition r
-B'e20. The membrane was heated at a temperature of 210°C for 3 hours in a stream of H2 by bubbling water at 7°C to remove Fe.
, 04 thin film (10) was formed.

For the O4 film, an external magnetic field of 100°C was applied parallel to the film surface, the magnetic field was removed, and the O4 film was then heated in the air at a temperature of 30°C for 3 hours to r -F.
a203NM was obtained. For comparison, 504g of K, Fe was not brought into a residual magnetization state, but r-
yθ20! A film was formed.

The two types of r-Fe2O mentioned above, the Ha of the film, α,
The value of S'' is shown in the 1g table. Here, Jat and %Co were added in addition to Os.

γ-1i″e in the case of residual magnetization with Fe, 04 film
Regarding the 304 film, the magnetic properties were measured in a direction parallel to the magnetization direction. In both samples, by magnetizing Fe, 04, H increases by about /θ%, b increases by /E ~%, and α increases by 7%.
A hysteresis loop with good rectangularity and a decrease of 7 to 21% was obtained.

Example 5 Using a 99.9at% OFe plate as a target, 3
An α-Fe205 thin film was formed by reactive sputtering in a mixed gas atmosphere of 0% Ar+3θ%02.

The diameter of the target was 27 cm. DB was added into the formed film by placing cotton, 9at, % O8 powder on the target. Sputtering atmosphere pressure distance X 10□5
Torr, the sputtering power was /kW, and the sputtering method was a high frequency magnetron method. The substrate is an alumite-coated HT alloy disk with a diameter of 2/2, and in order to keep the film thickness distribution constant in the circumferential direction, the speed of /θ rpm during sputtering is
I rotated it. By sputtering for 3 minutes, 0. /7 μm thick α-Fe20. A thin film was formed.

The amount of 06 added was controlled by the amount of 0s powder placed on the target.

The amount of O8 added is 0.37 and 0.7 in the ratio of metal elements only.
0°/, s, 2. t at,% α-Fe20. The thin film was reduced to a Fe,04 film by heating for 3 hours at a temperature of SO 0 C in a stream of H2 bubbled with water at 7 0 C, and then heated for v hours in air at a temperature of 310 0 C to r- A Fe205 thin film was formed. This γ~Fe2O,
The substrate on which the film was attached was cut into a j x j w angle, and an external magnetic field of + koe was applied parallel to the film surface, the magnetic field was removed, and the film was then heated in the air at a temperature of 200 °C for 1 hour. .

The magnetic properties before and after this reheating treatment are shown in FIG. 2 with respect to the amount of O8 added. As can be seen from FIG. 2, after the reheat treatment, HO and S 2 increase, and α decreases. Here, curves A, B, and O show the secondary examples that have been oxidized and have curved lines.

E and F show examples in which reheat treatment was performed after applying an external magnetic field after oxidation treatment according to the present invention.

, Qo -Ou -Ti-added γ-F,e with the conventional oxidation treatment as described in 1.
, 20. In the thin film, S 7r 0.77 te was obtained, but
(t31 In the present invention, S'20.Fe1 was obtained when the Os addition bar was in the range of 0.37 at.% or more.

Example 4 By the same manufacturing method as in Example 2, α-Fe20. After forming a thin film, it was heated for 3 hours at a temperature of 0°C for 2 nights in a H2 stream with water bubbled at 7°C to reduce it to a Fe3O4 film, and then heated for 1 hour at a temperature of 3io°C in the air. r-Fe2
An O3 thin film was formed. The substrate on which the γ-Fe205 thin film was attached was cut out into a square lx1 m square, and F parallel to the film surface was cut out.
After application of an external magnetic field of koe, the magnetic field was removed and subsequent heating was performed in the air at a temperature ranging from 110°C to 3jO°C for 1 hour. FIG. 3 shows the relationship between the temperature of this reheat treatment and the magnetic properties.

When the reheat treatment temperature is iro℃ or higher, Hc and S
increases and α decreases, and becomes almost constant above 210°C.

Next, we changed the magnetic field applied to the sample before reheating, and when the reheating treatment was kept constant at −jO℃ in the air for 1 hour, the external magnetic field applied to the sample and (/l) after reheating The relationship between the magnetic properties and the magnetic properties is shown in Figure 1.

Here, the external magnetic field is shown normalized by r -Fe2O before reheat treatment and the coercive force of the film. When this value is o3 or more, the rectangularity of the hysteresis loop begins to improve, and when it is 2.0 or more, it becomes a constant value. Reached.

As shown in Examples 1 to 4, imparting magnetic anisotropy by magnetizing the sample to the oxidation heat treatment step is a method that has been mainly used in the past for Co
, Ti, Ou, etc. added γ-Fe20. This phenomenon is not detected in thin films or r -Fe2O thin films without additives, and is markedly observed only in O8-added yarns.

Furthermore, the influence of sputtering conditions and reduction heat treatment conditions is small. That is, the sputtering atmosphere composition is 100% 0. to 90% Ar + 10% 0□, the sputtering atmosphere pressure is in the range of 0.5 - 10 -'' J By heating the sample for a long time and adding a treatment to magnetize the sample in the subsequent oxidation treatment process, γ-Fe2 with magnetic anisotropy in a certain direction is produced.
0. A thin film could be obtained.

Example 5 A Fe6o4 film was formed under the same manufacturing conditions as in Example 1, and the Fe,04 film was moved in the radial direction to magnetize it in the circumferential direction of the disk.

The core width of the head is 370 μm, and the gap length is. , 1μm
The number of turns per coil was 72. [Speed 1. j m/s, it floated with a flying height of o, irμm. Head material is Mn
-Zn ferrite. Disc diameter/90 m
A range of 200 trwr was magnetized with direct current. The final current value was sOmA. This disk was oxidized in air at a temperature of 370° C. for 1 hour to obtain γ-Fe20.
A thin film disk was fabricated.

The electromagnetic conversion characteristics of this disk were measured using the same head and the same head flying height used for DC magnetization. The measurement positions are the diameter/9j ss with direct current magnetization and the diameter/buQv with the r -Fe, O, film formed in the demagnetized state.
There were two locations, one with m. Table 3 shows the measurement results of electromagnetic conversion characteristics.

As can be seen from Table 3, when magnetic anisotropy is imparted in the circumferential direction (diameter/9j arm), γ-Fe20. When a film is formed (diameter/1018
> Compared to VC, the recording density (D5o) is //λFRPM (F
luxReversal Per Millimete
r), solitary wave reproduction output: 0, JI mV, overwrite characteristics: -j dB, signal-to-noise ratio: -0 dB.

Here, the solitary wave reproduction output is the amplitude of the output waveform when the recording density is low and the waveforms that match each other do not interfere with each other. The density was shown.

(17) Overwriting characteristics mean that after recording a 200 FRPM signal,
A 900 FRPM signal is recorded on the same track, and the frequency spectrum of the playback output is 900 FRPM.
It shows the ratio of PM component to -00FRPM component.

The signal-to-noise ratio is defined as the voltage that is half the amplitude of the reproduced waveform when recording a 30 FRPM signal, and the frequency spectrum of the reproduced output, excluding noise from the measurement system and recording signal output, and It was taken as the ratio to the effective value of the noise voltage calculated only for the generated noise.

For comparison, conventionally used (Eo, Ti
.

The electromagnetic conversion characteristics of the O-added Fe20s thin film are shown as follows:
λ, Oat, % 00-2. Oat, % Ti −/J
at,% Ou-added system γ-Fe20. In the case of thin films,
Residual magnetization 2! ;00Gauss, α=J, 0. S
= o, 7t, Ha = tso The magnetic properties of Oe are obtained,
When the film thickness is 0.17 μm, the solitary wave reproduction output is ? mV
s Recording density 1020 FRPM, oil writing characteristics-J
OdB, the signal-to-noise ratio was 113 dB. Therefore,
Os addition according to the present invention - Fe20. The thin film I tt
Ti-Ou-added r-Fe2O showed excellent electromagnetic conversion characteristics.

(Effect) As explained above, in the present invention, Fe added with O8
,04 thin film was oxidized to form γ-Fe20. During the process of forming a thin film, by applying an external magnetic field in the direction in which you want to impart magnetic anisotropy, or by applying a treatment to create a residual magnetization state,
The magnetic properties in the direction in which magnetic anisotropy is imparted are coercive force (H
a) and the rectangularity of the hysteresis loop are significantly improved.

When this thin film is used as a magnetic recording medium, the recording density,
This has the advantage of improving reproduction output, overwriting characteristics, signal-to-noise ratio, etc. In particular, the fact that magnetic anisotropy can be imparted simply by creating a residual magnetization state has the advantage that it is not necessary to perform heat treatment while applying a magnetic field, so the structure of the furnace is not complicated and mass production is easy.

[Brief explanation of the drawing]

Figure 1 is a diagram showing an example of a hysteresis loop, Figure 1 is a diagram showing the relationship between O8 addition amount and magnetic properties, Figure 3 is a diagram showing the relationship between reheat treatment temperature and magnetic properties, and Figure 3 is a diagram showing the relationship between reheat treatment temperature and magnetic properties. The ψ diagram is a diagram showing the relationship between an external magnetic field normalized by coercive force and magnetic properties, and FIG. 3 is a diagram showing the film material after reduction treatment with respect to the amount of O8 added and the humidity of reduction treatment. A: aCZ before reheat treatment B: 88 before reheat treatment, O: α before reheat treatment, D: Ha% after reheat treatment E: S″ after reheat treatment, F...α after reheat treatment. Patent applicant: Nippon Telegraph and Telephone Public Corporation Figure 4 Tatoon' PEtk-4 I-man (4 stones Mr. Kazuo Wakasugi, Commissioner of the Japan Patent Office, 2015, 2013, 2003, 2003, 2013, 2003, 2003, 2003, 2003, 2003, 2003, 2003, 1993, 1993, 1993, 1997, 1997, 1994, 1994, 1997, 1997, 1997, 1994, 1994, 1997, 1994, 1994, 1994, 1994, 1994, 1994, 1994, 1994, 1994, 1997; Relationship with Patent Applicant (422) Nippon Telegraph and Telephone Public Corporation Core ° Supplement "F""' As shown in Attachment 1, ``Example KO'' on page 1, line d of the specification has been changed to ``implementation f! 6JJ.'' 2. Add the following sentence after the 3rd line of page 1f of the same page: ``Example 6 α-Fe203 containing 80% Os was prepared by the same method as in Example 3. A thin film was formed.This α-F・203
The thin film was heated to 22k''C for 3 hours in a stream of H2 bubbled with water at /''C to reduce it to an Fs 304 film, and then heated to 310°C for 9 hours in air to form a γ-Fe20B thin film. was formed. The substrate on which this γ-Fe2O3 film was attached was cut out to a gxg sieve angle. After applying an external magnetic field of #KOe parallel to the film surface, the magnetic field was removed, and then the temperature was kept at 100℃ in the atmosphere for 7 days.
heated for an hour. The temperature changes of He near room temperature before and after this reheating treatment are shown in curves iG and H in FIG. 6, respectively. For comparison, γ-F@20 with % Q*g aL% Co added
The temperature change of He in the three thin films is also shown in Fig. 6 as curve i$11. q, zaat, %Co-added γ-Fe203 thin film is made by placing a Co pellet on the Fe target, and α-Fe
The reduction temperature from 203 thin film to F・304 thin film was set to 30θ℃.
It was formed by the same manufacturing method as in Example 3 except for the following. As is clear from Fig. 6, even when almost the same Ha is obtained at room temperature, the 08-doped γ-F 203 thin film is superior to the co-doped -F 203 thin film regardless of whether reheat treatment is performed.
1) The temperature change of He was smaller than that of the e2es ftk film. Regarding temperature changes in magnetic properties other than He, such as S, α, and saturation magnetization, the three types of samples described above exhibited similar behavior, and no significant differences were observed. Hc is a magnetic property that has a large effect on the recording density, and it is necessary to keep its temperature change as small as possible in order to reduce heating demagnetization of the disk medium. From this point of view, by addition of 〇-, r = H of Fe2O3 thin film.
It can be seen that increasing e is more advantageous than the conventionally used addition of Co. Example 7 The ratio (at, %) of only metal elements is 2.30! + -0
,! r Ru -Il, α-I-F@ with θCo added
203 membrane was produced. The manufacturing conditions are the core a used in Example A.
The conditions were the same as in Example 1, except that the Oi and Ru pellets were placed on the Co-added target. This α-Fe20a M was heated to 210°C for 3 hours in a H2 gas stream bubbled with water of /''C to F
An e3O4 film was obtained. This Fe3O4 film is
After applying an external magnetic field of +KOa parallel to the film surface, this magnetic field is removed to bring the Fe3O4 film into a residual magnetized state, and then heated in the atmosphere at 30θ°C for 3 hours to form an r -Fe2O3 film. Obtained. For comparison, in a γ-Fe2O3 film formed by performing three oxidations in the atmosphere without applying magnetic field treatment, He = , 2j and 0.
0e, S"=0.IQ, α=/, 1, and after magnetic field treatment He=λ6θ00e. S"=0.95. α=waste was obtained as the magnetic property in the direction parallel to the magnetic field treatment before heat treatment. In other words, the same magnetic field treatment effect as when adding %Oi+ alone is obtained when Co or Ruri:iM
It was also obtained when combined with sardines. Example g The ratio of only metal elements (a't, %) is 0. , l Os
10. A γ-Fe2'03 film in which kCo was added to kRu10 was fabricated. The manufacturing conditions in this example are shown in Table 1I.
The substrate was an alumite-coated A1 alloy disk with a diameter of J/cm. In order to equalize the film thickness distribution in the circumferential direction of this disk, the disk was rotated at a rotation speed of 10 rpm during sputtered film formation. After reducing the sputtered film (α-Fe203) to Tt Fe3O4, the sample was cut into a tXttm square along with the substrate, and after applying an external magnetic field of QKOe parallel to the film surface, the magnetic field was removed to create a residual magnetization state. Sample 1 is a γ-Fe2O3 film formed by oxidation in the atmosphere. Table 5 shows the magnetic properties of these samples 1 and 1, in which sample 7 is a γ-F.203 film oxidized without the above-described magnetic field treatment. Table 5 O, ko Os -0,! r Ru 6 /*k
For Co-added sample 1, the measurement magnetic field was 4! applied before heat treatment. The measurement magnetic field was parallel to the external magnetic field of KOe, and for sample λ, the measurement magnetic field was applied in an arbitrary direction parallel to the film surface. In sample l, compared to sample -, He and S-% increase, and α
decreased, and the rectangularity of the hysteresis loop increased. Such an effect was also observed in the 08 film alone or in the Og+Co composite addition γ=Fe2O3 film. In addition, °0. core aL%
Os +OAr at, %Ru 10/,! ;at,%
By placing only the 01 piece on the CO-added γ-I-FezO3 thin film disk and the Fe target, the amount of O1 added was reduced to a
The abrasion characteristics of the disk surface were evaluated for the y'' Fe2O3 thin film disk, which was formed using the same manufacturing method as Sample 1, except that the y'' Fe2O3 thin film disk had a diameter of 29 mm. Mn-Zn
A ferrite ball was pressed against a disk surface rotating at a circumferential speed of /B/sec under a certain constant load, and after 1000 passes, the wear depth of the disk surface was measured using a surface roughness meter. FIG. 7 shows the relationship between the ferrite ball load and the wear depth. 0*? a t 0.2ato%0 0.0, t at, %Ru185at than the 8%Os-added film (song MA)
e%C. It can be seen from FIG. 7 that the additive film (curve IJB) has a wear depth that is approximately 100% smaller and has an increased film strength even under the same load. In other words, it is expected that the flying height of the head will decrease as recording density increases;
The probability of accidental head-to-media contact would also increase. Increasing the strength of the media is believed to increase its resistance to such accidents. 3. On the evening line of the same page, "Diagram." 71 of disk media
FIG. 3 is a diagram showing the relationship between the wear depth due to the No. 241 ball and the ferrite ball load. ” is corrected. 4. Correct "α." in the first line of the same page to "α," and add the following after the same. [G.../, k ata % 佽 addition γ-! -Fe203
He before reheating of thin film % H.../mka aL% Ha after reheating of O1-added γ-F・203 thin film. I '''11.t&t, %Co added γ-Fe203 thin film Ha ()O) Fig. 7 Ferrite load (yf) IJ JIJ l:)IJ Humidity temperature 0C)

Claims (1)

[Claims] 1) γ-Fe20. In the method for manufacturing an iron oxide magnetic thin film, which forms a thin film mainly composed of Fe to which Os is added, before or during the oxidation treatment,
1. A method for producing an iron oxide magnetic thin film, which comprises applying an external magnetic field to a thin film containing 04 as the main component. 2) In a method for producing an iron oxide magnetic thin film in which a thin film mainly composed of r-Fe205 is formed through a step of oxidizing a thin film mainly composed of Fe3O4 to which Os is added, O8 is added after the oxidation treatment. A method for producing a characteristic iron oxide magnetic thin film.