JPS5971128A - Vertical magnetic recording medium - Google Patents

Abstract

PURPOSE:To obtain an excellent recording and reproducing characteristic by forming the ''Permalloy'' film in a double layered film medium formed with the ''Permalloy'' film between a substrate consisting of a non-magnetic material and a Co-Cr vertically magnetized film into a multi-layered film construction. CONSTITUTION:A ''Permalloy'' film 10 of the three-layered construction wherein three layers of ''Permalloy'' films of 400Angstrom for each one layer are superposed via a Co-Cr vertically magnetized film having 0.1mum film thickness is disposed on a film substrate 8 consisting of a heat resistant high polymer material having 18mum film thickness. If a signal of 100 KFRPI is recorded and reproduced by a vertical head of an auxiliary magnetic pole excitation type in the two-layered film medium having such construction, a reproduction output higher by 20dB is obtd. as compared with a conventional medium coated with iron oxide contg. Co. A reproduction output higher by 6dB is obtd. as well with the two-layered film medium of the same construction except that the ''Permalloy'' film is of a single layered construction and has 1,200Angstrom film thicness.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a medium for perpendicular magnetic recording that has excellent high-density recording characteristics.

Conventional Structure and Problems There is a perpendicular magnetic recording system as a magnetic recording system with excellent short wavelength recording characteristics. This method requires a perpendicular magnetic recording medium whose axis of easy magnetization is approximately perpendicular to the film surface of the medium. When a signal is recorded on such a medium, the residual magnetization is oriented in a direction substantially perpendicular to the film surface of the medium, so that the shorter the signal wavelength, the smaller the medium's internal repulsive magnetic field and the better the reproduced output. A Co-Cr perpendicular magnetic recording medium, which is called a single-layer film medium, is a perpendicularly magnetized film mainly composed of Co-Cr, which is deposited on a substrate made of a non-magnetic material by a sputtering method or a vacuum evaporation method (such as an ion-blating method). (including a method in which some of the evaporated atoms are ionized and deposited). In contrast to a single-layer film medium having such a structure, a so-called two-layer film in which a permalloy film 3 is provided between a substrate 1 made of a non-magnetic material and a Co-Cr perpendicularly magnetized film 2 as shown in FIG. It is known that recording efficiency and reproduction output can be improved by using a structure called a medium. In particular, when recording and reproducing using a known auxiliary pole excitation type vertical head, the recording efficiency is approximately 2.
The result is an improvement of 0 dB, and the reproduction output is improved by approximately 20 dB.

As mentioned above, excellent recording and reproducing characteristics can be obtained by using a double-layer film medium, but considering the increasing density and miniaturization of magnetic recording and reproducing devices, the characteristics are not sufficient and even better characteristics are required. characteristics were required.

OBJECTS OF THE INVENTION 3. It is an object of the present invention to provide a two-layer film medium having recording and reproducing characteristics even better than conventional two-layer film media. , Structure of the Invention The present invention provides a two-layer film medium in which a permalloy film is formed between a perpendicularly magnetized base film made of a nonmagnetic material and a perpendicularly magnetized film made of a non-magnetic material, in which the permalloy film has a multilayer structure. It is characterized by:

Description of examples The present invention will be explained in detail using FIGS. 2 and 3.

While the permalloy film 3 in conventional two-layer film media has a single-layer structure, the single-layer structure referred to here means that the permalloy film 3 is continuously deposited over the entire thickness of the permalloy film by sputtering or vacuum evaporation. The two-layer film medium according to the present invention has a structure as shown in FIG. 2, for example. In FIG. 2, the permalloy film 4 has a two-layer structure instead of a single-layer structure. Note that a structure with two or more layers is referred to as a multilayer structure. Furthermore, the two-layer structure refers to a film produced by not depositing a film continuously over the entire thickness of permalloy, but by stopping the deposition midway through the deposition and then starting the deposition again. The same applies to films with a structure of three or more layers. In this way, if the precipitation is stopped midway through the deposition, the surface oxidation 1 surface temperature will drop while the precipitation is stopped, and even if the precipitation is started again and the entire film thickness is formed,
A boundary layer is formed where precipitation has stopped. This layer is SEM
(scanning electron microscope) etc.

A permalloy film is made into a multilayer structure to create a two-layer film medium,
When recording and reproducing characteristics were measured, it was confirmed that the reproducing output was increased compared to when the permalloy film had a single layer structure.

This will be explained below.

FIG. 3 shows the reproduction output when the total film thickness and structure of the permalloy film are changed in a two-layer film medium.

Note that the thickness of the Co--Cr perpendicular magnetization film is constant at 0.16 μm. Further, recording and reproduction of signals was performed using an auxiliary magnetic pole excitation type vertical head, and the recording density was set to 50 KFRPI.

Note that 50KFRPI is a recording state of a digital signal in which magnetization is reversed 50,000 times per inch. Curves 6, 6, and 7 in Figure 3 represent the relationship between the total film thickness of the permalloy film and the reproduction output for two-layer media in which the permalloy film has a single-layer structure, a two-layer structure, and a three-layer structure, respectively. show. This figure shows that if the total thickness of the permalloy film is constant, the permalloy film has a multilayer structure, and the higher the number of calendars, the higher the reproduction output. A more specific example will be described below, which is believed to be due to the fact that the magnetic permeability μ is large, and as the film is made into a multilayer structure and the film thickness per layer is thinner, the μ of the film becomes larger.

First Embodiment A first embodiment of the present invention will be described with reference to FIG. In the figure, 8 is a film substrate made of a heat-resistant polymer material with a film thickness of 18 μm, and 9 is a C0-C film with a film thickness of 0.1 μm.
The perpendicular magnetization film 10 is a permalloy film with a three-layer structure in which three permalloy films are stacked at 40° per layer. An auxiliary pole excitation type perpendicular head is used to perform one
When recording and reproducing 00KFRPI signals, conventional Co
A reproduction output 20 dB higher than that of the media coated with 1-iron oxide was obtained. In addition, e
A dB higher reproduction output was obtained.

Second Embodiment A second embodiment of the present invention will be described with reference to FIG. In this case, the fourth
It has the same structure as the figure. Here, the Ti film 11 is Co-Cr
This is provided to improve the orientation of the perpendicularly magnetized film. An auxiliary pole excitation type perpendicular head is used to perform one
When recording and reproducing the 00KFRPI signal, the conventional CO
A reproduction output 23 dB higher than that of the coated medium containing iron oxide was obtained.

Effects of the Invention According to the present invention, a perpendicular magnetic recording medium with excellent recording and reproducing characteristics can be provided.

[Brief explanation of drawings]

Page 7 Figure 1 is a cross-sectional view showing the structure of a conventional magnetic recording medium, Figure 2
3 is a cross-sectional view showing an example of the structure of a magnetic recording medium according to the present invention, FIG. 4 and 5 respectively show the first embodiment of the present invention. FIG. 3 is a cross-sectional view of a magnetic recording medium according to a second example. 1.8...substrate, 2,9...perpendicular magnetization film, 3°4.1o...permalloy film. Name of agent: Patent attorney Toshio Nakao and one other person
Hoku 5 7k Otsu

Claims (1)

[Claims] A permalloy film is formed on a non-magnetic substrate, and CO and Cr are formed on the permalloy film directly or through a non-magnetic layer.
What is claimed is: 1. A perpendicular magnetic recording medium, characterized in that a perpendicular magnetization film containing as a main component is formed, and the permalloy film has a multilayer structure.