JPS6184005A - Magnetic recording material - Google Patents

Abstract

PURPOSE:To obtain desirable characteristics as a magnetic material having strong one axis anisotropy for a vertical magnetic recording medium by using the c-axis as a magnetizable axis in the inter-metal compound whose crystalline structure belongs to the tetragonal system. CONSTITUTION:For example, the Mn, Al, and Ga crystal structure compound having a Cu2Sb-type crystalline structure which consists of constitutent elements such as Al, Mn, Ga or Ge, etc. possesses a pillar-shaped structure in c-axis direction. The magnetic atoms Mn which fit in the positions of the Cu exist densely in the c-plane. Those atoms form a film plane which possesses a strong one-axis anisotropy, as an axis of easy magnetization in the c-axis direction. With this structure, the magnetized film possesses most desirable vertical magnetic characteristics and the recording reproduction characteristics of this metal film-type, while vertical magnetic recording medium show the maximum output in the vicinity of the approx. 4MHz.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magnetic recording material used particularly for perpendicular magnetic recording media.

[Prior art and its problems]

In recent years, there has been a strong demand for high-density recording in the field of magnetic recording, and perpendicular magnetic recording has been actively researched to replace the conventional recording method, horizontal magnetic recording. In other words, in the short wavelength region where high-density recording can be performed, conventional magnetic recording media have the problem of self-demagnetization, and there has therefore been a strong demand for perpendicular magnetic recording media that are less prone to such problems.

The magnetic material used in such perpendicular magnetic recording media needs to have strong uniaxial crystal anisotropy, where the saturation magnetization is MS, the -axis anisotropy magnetic field is Hk, and the crystal anisotropy constant is Let Ku be Hk)4πMs or Ku)2πM
It is necessary to satisfy the condition S2. As a material that satisfies these conditions, Co-
There are Cr alloys, etc.

However, since Co-Cr alloy is based on CO, it is more expensive, and because it is hard, it causes excessive wear on the magnetic head, causing problems in runnability and durability. It is not satisfactory in terms of strength and even magnetic properties.

Although research is being conducted on adding molybdenum, tungsten, tantalum, and other elements as third components to Co-Cr alloys, mainly to solve problems with magnetic properties, no proposals have been made that are fully satisfactory. It has not been.

[Disclosure of the invention]

The present inventor has discovered that an intermetallic compound consisting of constituent elements such as At, Mn, Ga, or Ge, and which is particularly tetragonal and has a Cu2Sb type crystal structure, and whose C axis is the axis of easy magnetization. , which exhibits strong uniaxial anisotropy, has been found to be extremely desirable as a magnetic material for perpendicular magnetic recording media.

For example, MnA with a Cu f S b type crystal structure
As shown in Figure 1, the crystal structure of tGe is C
It has a columnar structure in the axial direction, and magnetic atoms Mn that enter the Cu position are densely present in the C plane, forming a film surface, and the C axis direction becomes the axis of easy magnetization, resulting in a strong uniaxial magnetization. It can be seen that it has anisotropy and is extremely desirable as a magnetic material for perpendicular magnetic recording media.

[Example 1] In, At, and Ge were each weighed in equal atomic amounts, placed in a quartz tube, sealed under vacuum, and weighed approximately 1
It is heated to 400° C. to melt it, and then rapidly cooled and annealed to obtain an ingot of M n A tG e.

Then, this MnA tOe ingot is placed in, for example, an RF magnetron sputtering device, and sputtered under predetermined sputtering conditions to form a layer of about 0.2 μm thick on a nonmagnetic substrate.
A MnAtGe perpendicular magnetization film was constructed.

A hysteresis curve obtained by applying a perpendicular external magnetic field to this perpendicularly magnetized film is as shown in Fig. 2 (with demagnetizing field correction of 4πM s), which shows the ratio of the saturation magnetization Ms to the residual arsenic Mr. Mr/Ms is 0.93, Ms
is 250 emu/cc, and the coercive force Hc is 1600 oersted.

In other words, this magnetized film exhibits desirable perpendicular magnetic characteristics, and when we investigated the recording and reproducing characteristics of this metal thin film type perpendicular magnetic recording medium using a ring-type magnetic head made of Sendust, we found that the characteristics were as shown in Figure 3. It shows a large maximum output near about 4 MHz, which is extremely desirable.

Further, when the hardness was examined, it was found that it did not cause problems with wear of the magnetic head, and there were no problems with runnability or durability.

[Example 2] Mn, A7. A predetermined amount of Ga and Ge is vacuum sealed in a quartz tube, heated to about 1400°C to melt it, and then rapidly cooled and annealed to obtain an MnAtt-xGaxGe ingot. In the same manner as above, MnAt with a thickness of about 0.2 μm was deposited on a nonmagnetic substrate.
A 1-x G ax Oe perpendicular magnetization film was constructed.

A vertical external magnetic field is applied to this perpendicularly magnetized film to obtain a hysteresis curve, and the coercive force Hc and saturation magnetization Ms are determined as shown in FIG. According to this, when the amount of Ga increases, Ms decreases, but Ha does not decrease as much.

Furthermore, when examining the recording and reproducing characteristics of a perpendicularly magnetized metal thin film type perpendicular magnetic recording medium having a composition of MnAtCLII GaO,2Ge, for example, it is as shown in Fig. 3, and the recording and reproducing characteristics are approximately 4 MHz.
It is desirable to have a large maximum output in the vicinity.

Further, when the hardness was examined, it was found that it did not cause problems with wear of the magnetic head, and there were no problems with runnability or durability.

〔effect〕

It is low cost and provides a desirable perpendicular magnetic recording medium.

[Brief explanation of the drawing]

1 to 4 are explanatory diagrams showing the characteristics of the magnetic recording material according to the present invention.

Claims (2)

[Claims] (1) A magnetic recording material which is an intermetallic compound, whose crystal structure belongs to a tetragonal system, and whose c-axis is an easy axis of magnetization. (2) The magnetic recording material according to claim 1, in which the intermetallic compound has a Cu_2Sb type crystal structure.