JPS61258387A - Photomagnetic recording medium - Google Patents

Abstract

PURPOSE:To obtain a photomagnetic recording medium which is crystallo graphically stable in a thermal writing/temperature rising mode with a large Kerr revolving angle and also stable in a chemical mode like oxidation, etc. with reduced deterioration due to changes with time, by forming a thin film shown by PtxMnySbz (0<x<=0.30, y>=0.30 and z>=0.30). CONSTITUTION:A thin film shown by PtxMnySbz is formed on a substrate. These (x-z) are selected out of 0<<=0.30, y>=0.30 and z>=0.30 respectively. Furthermore, the (x) is selected preferably within a range of 0.20<=x<=0.27. Such a photoelectric recording medium is obtained by using an alloy target of Ptx'Mny'Sbz' or an alloy Mny'Sbz'. It is also available to distribute small Pt pieces on a sintered substance to secure a total target surface area ratio equal to Ptx'Mny'Sbz' (x'+y'+z'=1). The thickness of this thin film is set at 300-5,000Angstrom .

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to a magneto-optical recording medium.

(Prior art) Signal detection method As a writing method, the rotation of the plane of polarization that occurs in a magnetic material in response to the state of magnetization of the same alloy is detected, or the rotation of the plane of polarization is magnetized so that the desired rotation of the plane of polarization occurs. done by This method is called magneto-optical recording, and such magnetic recording media can also be used to modulate the plane of polarization. In magneto-optical recording, amorphous rare earth-transition metal thin films (Tb-Fe, Gd-Co), MnB1#
The system is known.

Amorphous rare earth-transition metal magnetic materials have no grain boundary noise.
Crystallographically stable during hot writing and suitable for physical vapor deposition (P)
However, the problem is that the Kerr rotation angle, which is the rotation angle of the polarization plane of the reflected light with respect to the polarization plane of the incident light, is small, and without a protective film, deterioration over time due to oxidation or the like is severe. In addition, although the MnB1 system has a large Kerr rotation angle, it has large grain boundary noise and is crystallographically unstable during thermal writing, so there is very little nitrification due to multiple writing, but the light absorption coefficient is small and the thickness is Membrane (about 0,!μm)
Otherwise, the light absorption required to raise the temperature of the medium itself will not occur. Also PVD, C! There is no report that a perpendicularly magnetized film has been obtained by the VD method, but by a single crystal growth technique. Therefore, it is difficult to increase the area, the productivity is low, and the cost is high.

DoMn:S)! :/:/:/) has a special semimetal-like band structure and exhibits an abnormal Ker at room temperature due to selective electric dipole transition accompanying the splitting of energy levels within the valence band.
Bulk crystals have been reported as a material in which the r effect is observed (J, Appl, phys,, j
! (6), 21!7 (/Rizau), J-MagM
ag Mat, 31/(/ri13)Ap
pl, Phys, Lett.

≠2 (2), 202. /9♂3].

Therefore, the present inventors conducted various studies in order to obtain a Pt-Mn-13b-based magneto-optical recording medium that is stable, has a large Kerr rotation angle, and can be reduced in cost, and has finally arrived at the present invention.

That is, the gist of the present invention is that PtXMnySbZ (0<
1≦0. J O, 31'≧0.30, IM≧0.3
A magneto-optical recording medium is formed by forming a thin film represented by 0).

(Structure of the invention) The present invention will be explained in detail below.

The method for manufacturing the magneto-optical recording medium of the present invention mainly includes the well-known sputtering method, vapor deposition method, ion plating L/-f method,
The so-called physical vapor deposition method (Physical vapor deposition method) such as plasty ion beam method
ical Vapor Deposition PV
D method) is used. In the sputtering method, ions such as Ar are bombarded with a target material corresponding to the thin film material to be deposited to knock out atoms of the target material (= sputtering).
The generation of ions such as Ar, which forms a film by depositing sputtered atoms on the substrate, is 1o-
A gas with a partial pressure of L to """ Torr is introduced into a sputtering vacuum chamber, and a direct current or high frequency alternating current electric field is applied to the target (T
arget) and a counter electrode (usually a grounded substrate support or vacuum vessel), producing a known glow discharge. When forming the PtxMny8bz thin film of the present invention, a target having an area ratio or composition ratio of Ptx'yiny'sbz' having a composition corresponding to the composition ratio is used.

Each element jumps (
= sputtering) Since the misbatter rate is different, consider this sputtering rate to determine the desired thin film composition! + 7 +
Target composition 7, y, and finish are determined corresponding to Z. This X + 7 * z is (7<X≦0.30, y
≧Q, 30, z≧0.30, X is preferably O≦X≦0.30, more preferably 0.20
Selected from the range of ≦X≦0.27.

To obtain the magneto-optical recording medium of the present invention, Pt ny'S
An alloy target of Mn7' may also be used.
Pt small pieces are placed on the sb alloy or sintered body, and the overall target surface area ratio is PtfMny'81b
Z'(x!+7'+i=/) may be blended as much as possible. For the purpose of low rotation, a target can be used with a combination of small pieces or alloys between PT and Mn5b0. The ions used for sputtering are usually inert gas such as Ar. The power for discharge varies depending on the gas pressure (degree of vacuum), target size, and substrate area, but ranges from several tens of W to several hundred.

In the present invention, substrate materials on which thin films are deposited include glass, polycarbonate (PC), polymethyl methacrylate epoxy, polyimide, polyamideimide, etc., preferably transparent resin substrates with low optical birefringence, etc., as magneto-optical recording materials. Various known materials can be used. These substrates may be provided with optical birefringence (groups) as is known in the optical memory technology field.
usually! Selected from approximately 00 to s, o o o x.

As mentioned above, the method for manufacturing the magneto-optical recording medium of the present invention is not limited to the above-mentioned sputtering method, but any film forming technique known in the field of thin film technology may be used.

Using the raw materials Pt, Mn, and Sb as evaporation sources, each or an alloy of these is placed in a heating crucible and heated by electrical resistance.9) The raw materials are evaporated in vacuum (10 Torr or less) by heating with an electron beam. It is possible to create a desired alloy film on a substrate. It is also possible to ionize the evaporated atoms (clumps) during film deposition on the substrate and accelerate them using an electric field while they reach the substrate. Compared to sputtering, these evaporation methods in a broad sense are difficult to control the composition of the film to be formed, and it is preferable to evaporate each component independently (and simultaneously) while monitoring the evaporation rate of each component for film thickness (usually using a quartz crystal). The temperature of the crucible is adjusted while detecting the crucible (a commercially available product using an excavator is used), and the ratio of each component for the amount of evaporation is adjusted.

The thin film thus obtained can then be thermally annealed to control its crystallinity.

Normally, a thin film immediately after deposition solidifies (solidifies) without sufficient diffusion time during the deposition of atoms (clumps), resulting in disordered crystallinity, multiphase crystals, or amorphous. There are many cases.

As for magneto-optical recording media, it is not clear whether a film with such disordered crystallinity or a film with high integrity is preferable, but in order to obtain a film with higher crystallinity, In the case of the medium of the present invention, the temperature is too to 700°C, preferably 4Lo.

Thermal annealing is performed under vacuum at ~100°C for /-20 hours.

The PtxMny8bz thin film obtained by the above method is 0 (x≦0.30, y≧0.30, z≧0
．． 30, providing an excellent magneto-optical recording medium with a large Kerr rotation angle (therefore, an improved S/N ratio). The medium according to the present invention can also be used by further laminating other magnetic materials. For example, by stacking with a magnetic material such as an amorphous rare earth transition metal alloy (such as TeFe system) that has high recording sensitivity and coercive force or a small Kerr rotation angle, l) a protective film of an amorphous rare earth transition metal film can be formed. c) Furthermore, by placing the medium according to the present invention on the light incident side, the Kerr rotation angle of the amorphous rare earth transition metal film can be improved.

(Example) Hereinafter, the present invention will be explained in more detail with reference to Examples.

Example 1 PT sheet (!x
j X O, 1 m) and vacuum Wl is
After evacuation to 'Torr, a PtMn13b thin film was formed on the oxidized S1 wafer substrate by co-polar RF sputtering. Sputtering conditions were rf power, 10
OW.

Atmosphere Ar (Tata, Tata%), gas pressure j X/0
"-" Torr, substrate temperature 100° C., distance between target and substrate, and jan. The thickness of the prepared thin film was 0Q-2≦00X, and it was heated at 00°C for 10 hours in the evening.
Annealed in vacuum. In addition, in the sputtering target that was closed at this time, the area ratio of the MnSb sintered body and the PT small pieces was /: 0.012.

X in the obtained recording medium PtXMnyS bz
When the value of +7 +2 was measured using an induced radio frequency plasma emission spectrometer (Engineering CP), it was found to be X20.2.

y=0.33. z=θ, lA 3. Further, FIG. 1 shows the results of measuring the Kerr hysteresis curve when a light beam (wavelength: 6 j 3 nm) was incident on the film side of this recording medium. Kθrr rotation angle (H=p g−O
The Kerr rotation angle (θk) in a) was 0.2 (deg).

(Effects of the Invention) The magneto-optical recording medium according to the present invention is crystallographically stable during heating during thermal writing, has a large Kerr rotation angle, and is stable even during chemical reactions such as oxidation, so that it has little deterioration over time.

Furthermore, a large-area thin film can be manufactured simply and easily, and can be manufactured at low cost and with high productivity.

[Brief explanation of drawings]

FIG. 1 shows an example of a hysteresis curve of a recording medium according to the present invention. Applicant: Mitsubishi Chemical Industries, Ltd. Agent: Patent attorney Yo Hase - and 1 other person

Claims (1)

[Claims] (1) Pt_xMn_ySb_z (0<x≦0
．． 30, y≧0.30, z≧0.30).