JPH0447521A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To lessen the degradation in reproduced output at the time of high- density recording and to improve overwriting characteristics by laminating Cr thin films having the coercive force increasing from the lower layers toward the upper layers on an underlying layer consisting of the Cr thin film. CONSTITUTION:The Cr thin films 3 to 5 having the coercive force larger from the lower layers toward the upper layers are laminated on the underlying layer 2 consisting of the Cr thin film provided on a nonmangetic substrate 1. For example, Co, Ni and Cr are used as the Co alloy and the coercive force of the respective Co, Ni and Cr layers is changed by changing the substrate temp. Then, recording and reproducing are executed by the layer having the high coercive force of the surface layer part at the time of high-density recording. The information recorded in the layer of the deep layer part having the low coercive force is easily rewritten even if the leak magnetic field from the magnetic head is small. The magnetic recording medium having the good overwriting while maintaining the high reproduced output at the time of the high-density recording is obtd. in this way.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention particularly relates to a magnetic recording medium with excellent high-density recording and reproduction characteristics.

[Conventional technology]

In recent years, as magnetic recording media have become more densely recorded, there has been a demand for magnetic recording media with higher coercive force.

In order to satisfy this demand, thin film media manufactured by thin film forming methods such as sputtering are becoming more popular than conventional coated media coated with iron oxide acicular particles.

l.

By the way, the magnetic recording medium C (hereinafter referred to as metal sputtered medium) produced by this sputtering method is generally a Cr, Co alloy thin film on an A/-M9 substrate provided with a hardened Ni--P underlayer. I! The magnetic properties are controlled by the thickness of the Cr thin film and Co alloy thin film and the film forming conditions (substrate temperature, sputtering gas pressure, etc.). For example, publications (I K B K T
rans-Mof・MhG・-23,, f; 1.
January 19&? , PL22~124)
KC? The change in coercive force when the film thickness of thin film and Co alloy thin film is changed is also reported in a publication (11th Japanese Society of Cardiac Magnetism Abstracts, P. 18 (November 1987)).
2 shows the change in coercive force with respect to substrate temperature, and it has been shown that a high value of 10,000e to 15,000e can be obtained as coercive force.

[Problem to be solved by the invention]

However, as the coercive force increases, the reproduction output at high recording densities increases, but a problem frequently arises in that override characteristics deteriorate.

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to obtain a magnetic recording medium with good override characteristics while maintaining a high reproduction output during high-density recording.

[Means to solve the problem]

The magnetic recording medium of the present invention includes a non-magnetic substrate, and 0rIv11! provided on the non-magnetic substrate. ! 00 alloy thin film having a larger coercive force from the lower layer to the upper layer is laminated 71 on the underlayer.

[Effect]

The magnetic recording medium in this FJA has a layer with a low coercive force in the deep part of the magnetic layer and a layer with a high coercive force in the surface part. In addition, the information recorded in the deep layer with low coercive force can be easily rewritten if the leakage magnetic field from the magnetic head is small, so there is no deterioration in override characteristics. It is.

[Implementation row]

An embodiment of the present invention will be described below with reference to the drawings. 1st
The figure is a cross-sectional view of a magnetic recording medium according to an embodiment of the present invention. It is a membrane layer.

Example 1 A with a hardened Ni-P underlayer provided as a non-magnetic substrate
t-M? A textured substrate was used, and Co6as N130 Cr7. aa
C of the composition of tchi! o hJt cr 'it: *Carbon was used as the protective film material. Control of the coercive force VC of each Co Ni Cr layer is performed by changing the substrate temperature9.

That is, first, a Cr thin film and a first-layer Co Ni Cr thin film were deposited using a sputtering method at a substrate temperature of 1 G°C.
Thick and thin 1i1 layer LlooOA 1st layer cQ Ni
(!rA thin film was formed at 167A, and then the substrate temperature was
℃ to form the second layer of CoNiCr thin film at 167A, and then the substrate temperature to 200℃ and the 8th layer of Co.
A Ni ar thin film of 167 Å was formed, and finally a carbon protective layer of 40 OA was formed to obtain a magnetic recording medium. In addition.

The sputtering gas pressure at this time was 10 mTorr.

12 degrees KCr between the 11th and second Co Ni Cr thin films and the second and third Co Ni Cr thin films
Everything was done 411 except that Cr thin film groove 1100A was formed.
A magnetic recording medium was obtained by forming a gX film under the same conditions as described above.

Comparative Example 1 A magnetic recording medium was obtained by forming a single layer of Co Ni Cr thin film (2000A) at a substrate temperature of 100°C.Other conditions were the same as in Example 1.

Comparative Example 2 A magnetic recording medium was obtained by forming a single layer of Co Ni Cr thin film f 2000 A at a substrate temperature of 00° C. for 500 years. Other conditions were the same as in Example 1.

The electromagnetic f-conversion characteristics and magnetic characteristics of the metal sputtering media obtained in Chemistry 1.2 and Comparative Example 1.2 were measured. ta
To measure the X-strike characteristics, the thin-film magnetic head was set at a full-circle relative speed f12.
1 m7w, flying noise 1 o, 5arne frequency LF: 3 MHz, HF 8 MHz. In addition, a vibrating sample magnetometer (VSM) was used to measure the divination characteristics.

The results of ta conversion characteristics and magnetic characteristics are shown in Table 2.

Below, the 16th line margin '1fPJ Both 1 and 2 have coercive forces set at a slightly lower value than Comparative Example 2, but are much larger than Comparative Example 1.

In terms of reproducing power, the reproducing specific power in LP is the same for both Examples and Comparative Examples, but in HF, Examples 1 and 8 have slightly lower reproducing outputs than Comparative Example 2, but compared to Comparative Example 1. It shows a big a. In the override, both Examples 1 and 2 were -30 dB or less, and Comparative Example 2 was -28 dB.
It shows good characteristics compared to dB.

In addition, in the above implementation gAjVC, N is used as the nonmagnetic substrate.
A with textured i-P hardened layer
/ -MP substrate, C062-5Ni as 00 alloy thin film
30 Cr? , 5 at% Co Ni Cr thin film has been described, but the present invention is not limited to this, and similar effects can be achieved even when applied to other substrates or other 00 alloy thin films.

Furthermore, in the examples, the coercive force of each 00 alloy thin film was controlled by changing the substrate temperature during film formation, but it may be controlled by other methods, for example, by changing the composition of Co or less. In the case of the 4° implementation row, a case in which three layers of 00 alloy thin films are laminated has been described, but the present invention is not limited to this, and the same effect can be obtained even if the case is applied to two or more layers.

〔Effect of the invention〕

As described above, according to the present invention, Cr1
Co alloy thin films with larger coercive force are laminated from the lower layer to the upper layer on the base layer made of il film and the base layer made of Cr1li film, so that the drop in reproduction output during high-density recording is small and override characteristics are achieved. A good magnetic recording medium can be obtained.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a hunting recording medium according to an embodiment of the present invention. In the figure, 111 is a nonmagnetic substrate, 21 is a base layer made of a Cr thin film, and 3) to 151 are 00 alloy thin films.

Claims (1)

[Claims] (1) A magnetic recording medium in which a Cr thin film and a Co alloy thin film are sequentially formed on a non-magnetic substrate, characterized in that the above Co alloy thin films are laminated in which the upper layer has a larger coercive force than the lower layer. Medium.