JP2886584B2 - Recording medium and recording device - Google Patents

Description

The present invention relates to a recording device for an information recording / reproducing device such as a computer and various electronic cameras, and is particularly suitable for high density and large storage capacity. Also, the present invention relates to a rewritable recording device that can be used in a wide temperature range.

(Prior Art) Magnetic materials are often used in conventional recording methods for mass storage devices. Regarding this method, for example, Ohmsha, “Magnetic Material Ceramics”, Sakurai, Kanamaru, P143
(1986).

Examples of using the oxide as the recording medium include:
JP-A-63-268087 discloses that recording and reproduction are performed at a temperature lower than the superconducting critical temperature using an oxide superconductor.

(Problems to be Solved by the Invention) In the case where a magnetic material is used in the above-mentioned conventional technology, the magnetization state of the magnetic material is used. From 1μ
A bit period of about m has been considered the limit.

In a recording method using a superconducting oxide, the medium is cooled to a temperature at which the superconducting state is exhibited, and in this state, oxygen ions and hydrogen ions are irradiated from a needle ion irradiation source to obtain a superconducting state and a normal conducting state. The two states of the state correspond to the binary signal of the binary system. Although the storage capacity can be increased by this method, the critical temperature of currently known superconductors is about
Only lower than 130K.

Therefore, in order to actually record, it must be cooled to a temperature lower than about 130K. For this reason, there has been a great problem in that a cooling medium such as liquid nitrogen or liquid helium must be used, or a special cooling device such as a helium refrigerator has to be used.

Further, in order to record using two states, a superconducting state and a normal conducting state, this method has a problem that multi-value recording cannot be performed. In addition, since recording is performed using oxygen ions and hydrogen ions, There is a disadvantage that optical input signals such as video cannot be directly recorded.

Therefore, an object of the present invention is to make the storage capacity larger than when a magnetic material is used, and to perform recording without using a special cooling medium or cooling device such as liquid nitrogen, liquid helium, or a helium refrigerator, and It is an object of the present invention to provide a recording apparatus which can cope with both signals and optical signals and which can easily rewrite signals.

(Means for Solving the Problems) The above object is achieved by the present invention described below.

That is, the present invention relates to an oxide of an oxide in which the content of oxygen and the crystal structure change in response to the intensity of an input electric field or an input light beam, and the change causes a change in electrical resistivity, optical transmittance, or optical reflectance. A recording medium having a layer, a recording medium having an oxide layer whose oxygen content and crystal structure change in response to the intensity of an input electric field, and an electric field applied to the recording medium, whereby an electric field is applied to the recording medium. A recording apparatus having a recording unit that causes a change in electrical resistivity, optical transmittance, or optical reflectance of a portion where an electric field is applied,
And a recording medium having an oxide layer in which the oxygen content and the crystal structure change in response to the intensity of the input light, and exposing the recording medium to light, thereby exposing the light of the recording medium. This is a recording apparatus having recording means for causing a change in electrical resistivity, optical transmittance, or optical reflectance of a part.

(Operation) The amount of oxygen contained in the oxide is controlled, and the crystal structure of the oxide is changed. The change in the crystal structure of the oxide and the change in the crystal structure of the oxide are used as a signal. To correspond to.

For example, in a YBa ₂ Cu ₃ O _7-x (0 ≦ x ≦ 1) material, when the x value is larger than 0.5, the crystal structure is a tetragonal structure, and when the x value is smaller than 0.5, the crystal structure is orthorh.
It is an ombic structure. The electrical resistivity near room temperature due to this change in oxygen amount is larger in the tetragonal structure.

And even in the same tetragonal structure, when the oxygen amount is reduced, the electric resistivity further increases. Further optical properties, for example,
As for the reflectance, the smaller the oxygen amount, that is, the larger the x value, the smaller the reflectance. The absorptance also changes depending on the amount of oxygen, like the reflectance. Such a change in physical properties is a small x value orth
The same occurs in the orhombic structure, and the change in the amount of oxygen can be controlled by applying electrolysis, applying current or irradiating light at any temperature of the oxide, and the amount of oxygen in the oxide can be controlled by the electric field and current. , Can be changed continuously by the intensity of an input signal called light.

The present invention records various types of information by utilizing changes in electrical and / or optical physical quantities such as electrical resistivity, absorptance, and reflectance caused by changes in the amount of oxygen in an oxide as described above. It is.

(Examples) Hereinafter, details of the present invention will be described with reference to examples.

Embodiment 1 FIG. 1 is a schematic view showing a recording method of the present invention.

1 is a needle-like electrode for writing / reading, 2 is an oxide, specifically, YBa ₂ Cu ₃ O _7-x , 3 is an electrode. In the present invention, gold (Au) was used. Reference numeral 4 denotes a substrate. Therefore, portions 2, 3 and 4 form a recording medium.

The method for producing the recording medium is as follows. First, chromium (Cr) is added to the glass (for example, Corning 7059) as the base.
And gold are deposited to a thickness of 10 nm and 300 nm, respectively, by a vacuum deposition method to form electrodes. Next, YBa ₂ Cu ₃ O _7-x is formed to a thickness of 100 nm by cluster ion beam evaporation.

An electric field of 2 V was applied between the needle electrode 1 and the electrode 3 at room temperature and in the air on the recording medium prepared as described above. In the portion where the electric field was applied, the oxygen content was reduced and the electric resistance was increased. When a bias voltage of 1 V is applied to a portion where no voltage is actually applied, a current of 10 ⁻⁶ A flows, but a current of 10 ⁻¹⁰ A or less flows in a portion where an electric field is applied. As a result, it was confirmed that the signal was recorded by the electric field of 2V and the signal could be read by the bias voltage of 1V.

To erase the recorded signal, the recording section may be heated to about 100 ° C. in an oxygen atmosphere. In order to erase all the signals, the entire recording medium may be heated. In the case of partial erasure, the discharge is performed to such an extent that no discharge occurs without irradiating a semiconductor laser or bringing the needle electrode 1 into contact with the oxide 2. Voltage may be applied.

Example 2 Silicon (Si) was used for the substrate, and YBa ₂ CU ₃ having a thickness of 200 nm was used for the oxide.
A recording medium was prepared in the same manner as in Example 1 except that O _7-x was used.

A 2.5 V pulse electric field (pulse width 5 ns) was applied between the electrodes 1 and 3 on this recording medium, and recording was performed. At this time, the value of the current flowing between the electrodes 1 and 3 changed as shown in FIG. 2 depending on the number of applied pulses. In this way, there was a 1: 1 correspondence between the number of applied pulses and the current between the electrodes, and multiplex recording was possible.

Example 3 The same recording medium as in Example 2 was used. Third
Various images were formed on a recording medium by a lens as shown. The exposure time at this time is 1/60 second. Thereafter, by scanning the same needle-shaped electrode as in Example 1 on the recording medium, an image similar to that formed on the recording medium could be reproduced. This means that the amount of oxygen in the medium has changed in proportion to the amount of light applied to the recording medium.

Note that the needle-like electrodes (not shown) X, Y, mounted on a movable scanning mechanism in the Z direction, 10 ^-3 nm in the Z direction, X
Positioning can be performed with a resolution of 0.02 nm in the Y direction.

Embodiment 4 FIG. 4 shows a configuration diagram of a recording apparatus of the present embodiment in FIG. Reference numeral 7 denotes an oxide insulator, which has a function of preventing oxygen from being desorbed from the oxide 2 of the recording layer to the outside and entry of oxygen from the outside. The base 4 is made of quartz glass, and the oxide 2
Is the same as in the second embodiment. The oxide insulator 7 is silicon oxide (SiO ₂ ) formed by RF magnetron sputtering, and has a thickness of 30 nm.

When an electric field is applied between the electrodes 1 and 3 by the tunnel current at the needle-shaped electrode 1 using the recording medium having such a configuration, a portion where the electric field is applied has a low electric resistance, and a portion where the electric field is not applied is a portion where the electric field is not applied. The electrical resistance was high, and the input signal of the electric field could be recorded by using the high and low resistance states by applying the electric field.

(Effects of the Invention) According to the present invention, the recording density can be improved by three to four orders as compared with the case where a conventional magnetic material is used.
In addition, unlike the recording method using the superconducting-normal conducting transition, it is not necessary to cool the recording medium to a low temperature, so that it can be used at room temperature. Further, since the oxygen amount can be continuously changed depending on the intensity of the input signal, multi-value recording is also possible.

Further, in the embodiments, the recording medium is prepared by a vacuum deposition method or a cluster ion beam deposition method. However, the present invention is not limited thereto, and various thin film preparation methods such as a sputtering method, a CVD method, and a coating method can be applied.

Further, the oxide is not only composed of Y-Ba-Cu-0, but also composed of In-Sn-0, Bi-Sr-Ca-0, T1-Sr-Ca-Cu.
It goes without saying that most oxides such as oxides composed of −0, Ti-0, etc. can be used.

Further, in the embodiment, the electrodes constituting the recording medium are used in the portions 1 and 3 as shown in FIG.
It is also possible to utilize the change in the electrical characteristics between (2) and (2).

[Brief description of the drawings]

FIG. 1 is a conceptual diagram in the case of electrical recording in the present invention, FIG. 2 is a diagram showing the relationship between the number of input pulses to be recorded and the current value, FIG. 3 is a schematic diagram in the case of recording by light, FIG. FIG. 3 is a schematic diagram when recording is performed using a Tonell current. 1: Needle electrode 2: Oxide 3: Electrode 4: Oxide 5: Lens system 6: Image signal 7: Insulator

────────────────────────────────────────────────── ─── Continued on the front page (51) Int.Cl. ⁶ Identification code FI G11B 11/08 G11B 11/08 (72) Inventor Takehiko Kawasaki 3- 30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc. ( 72) Inventor Keisuke Yamamoto 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc. (56) References JP-A-54-133134 (JP, A) JP-A-62-219344 (JP, A) JP-A-62-268087 (JP, A) JP-A-64-57438 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) G11B 9/00 G11B 9/04 G11B 7/24

Claims (9)

(57) [Claims] 1. In response to an input electric field or input light intensity,
A recording medium having an oxide layer in which the oxygen content and the crystal structure are changed, and the change causes a change in electrical resistivity, optical transmittance, or optical reflectance. 2. The recording medium according to claim 1, wherein the change in the oxygen content is a decrease. 3. A recording medium having an oxide layer whose oxygen content and crystal structure change in response to the intensity of an input electric field, and an electric field is applied to the recording medium, whereby an electric field of the recording medium is applied. A recording apparatus having recording means for causing a change in electrical resistivity, optical transmittance, or optical reflectance of a portion to which is applied. 4. The recording medium has a substrate, one electrode disposed on the substrate, and the oxide layer disposed on the one electrode. 4. The recording apparatus according to claim 3, further comprising another electrode that can be arranged on the layer of the object. 5. The recording apparatus according to claim 4, wherein said other electrode has a needle-like electrode. 6. The recording apparatus according to claim 3, further comprising an erasing means for erasing recorded contents recorded on a recording medium by using said recording means. 7. A recording medium having an oxide layer whose oxygen content and crystal structure change in response to the intensity of input light, and a light beam is exposed to the recording medium, whereby the light beam of the recording medium is exposed. Is the electrical resistivity, optical transmittance,
Alternatively, a recording apparatus having recording means for causing a change in optical reflectance. 8. A recording apparatus according to claim 7, wherein said recording means has an image forming optical system for exposing the recording medium to light rays. 9. The recording apparatus according to claim 7, further comprising an erasing means for erasing recorded contents recorded on a recording medium by using said recording means.