Patent Application
20090141387
This application claims the priorities of Korean Patent Application No. 10-2007-0122991 filed on Nov. 29, 2007, in the Korean Intellectual Property Office and Korean Patent Application No. 10-2008-0016793 filed on Feb. 25, 2008, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference.
1. Field of the Invention
The present invention relates to a nanoprobe-based heating apparatus and a heat-assisted magnetic recording head using the same, and more particularly, to a heating apparatus with a sharp nanoprobe, which is installed at a magnetic recording head of a magnetic hard disk drive to be able to heat an ultra-fine region of a recording medium very rapidly by applying heat together with a magnetic field.
This work was supported by the IT R&D program of MIC/IITA [2006-S-005-02, Development of THz-wave oscillation/modulation/detection module and signal sources technology]
2. Description of the Related Art
In the magnetic recording technologies, the recording density gradually increases and thus the size of unit recording bit of a recording medium recording unit information tends to be smaller. For example, when the recording density is 10 Gbit/in2, the unit recording bit has a size of about 200×300 nm2; when the recording density is 100 Gbit/in2, the unit recording bit has a size of about 75×100 nm2; and when the recording density is 1 Tbit/in2, the unit recording bit has an ultra-fine size of about 20×30 nm2.
If the physical size of the unit recording bit decreases, the number and volume of magnetic particles existing in the unit recording bit decrease, causing a thermal fluctuation. Consequently, the magnetic recording becomes impossible.
That is, in order to function as the magnetic recording apparatus, magnetic particles must maintain at least 10 years magnetization caused by a magnetic induction. However, if the size and volume of the magnetic particles decrease due to the increase of the recording density, the duration is exponentially decreased by the thermal fluctuation. Specifically, when the volume of the unit particle is decreased by ½, the duration around a threshold value is significantly decreased below several seconds in 10 years.
Such a phenomenon is called a superparamagnetism phenomenon. In theory, a recording density limit at which the recording is impossible due to the superparamagnetism phenomenon is about 200-300 Gbit/in2. Therefore, such a superparamagnetism phenomenon must be overcome in order to implement the recording density more than the recording density limit of 200-300 Gbit/in2.
One of methods for overcoming the superparamagnetism phenomenon is to use magnetic recording particles having a large magnetic anisotropic coefficient. Thus, the magnetization can be retained with a small number of magnetic particles, without thermal fluctuation, thereby making a high-density magnetic recording possible.
However, in this case, since a magnetic coercivity for magnetizing a magnetic material increases, a very strong magnetic field must be used for a recording/erasing operation, which increases the total size and weight of a recording head. In actuality, a recording head larger than a disk drive is necessary for implementing a recording density of Tbit/in2 level, which is impracticable.
What is thus required is a technology that can perform a recording operation by means of a weak magnetic field and maintain a magnetized state for a long period, while using a material with a large magnetic anisotropic coefficient. Such a technology makes it possible to implement a recording operation with a super high density of above Tbit/in2, overcoming the limit of a superparamagnetism phenomenon.
Recently, extensive research is being conducted to develop a heat-assisted magnetic recording (HAMR) technology that is evaluates as the most competent technology for solving the above limitations.
The HAMR technology applies heat to a recording bit portion together with a magnetic field to reduce a magnetic coercivity, i.e., a magnetic field necessary for a recording operation, thereby making it possible to perform a recording operation by means of a weak magnetic field. To this end, a technology is required that can heat/cool an ultra-fine region to about hundreds of ° C. very rapidly.
A related art method capable of rapidly heating a region of several tens of nm2 by means of laser beams is illustrated in
Referring to
When the recording medium 2 moves in ‘A’ direction, a light focus 6 is formed at the recording medium 2 by a laser beam radiated from the light source 5 such as a laser diode. After the recording medium 2 is heated by the laser beam, it is magnetized by a leakage magnetic flux generated from the recording head 2, under the condition of a low magnetic coercivity.
The light source formed by the laser beam must be very small in order to perform a high-density recording operation by means of the heat-assisted magnetic recording head 1.
However, a laser beam can be applied to rapid heating and rapid cooling, but cannot be applied to an ultra-fine region smaller than ½ of a wavelength due an optical diffraction limitation. Thus, it is nearly impossible to form a focus with a diameter of below 100 nm, even using a blue ultraviolet laser beam with a wavelength of 200 to 400 nm.
Therefore, a near field is used to solve the above limitation. However, when a near filed is used, an optical efficiency is too low to about 10−4 to 10−6 and an expensive and complex optical system must be installed for rapid heating and rapid cooling.
What is thus proposed is a heat-assisted magnetic recording (HAMR) technology for overcoming a superparamagnetism phenomenon that is the recording limit of a magnetic disk.
The HAMR technology applies heat together with a magnetic field when performing a data recording operation. In general, near-field laser beams are used to heat/cool an ultra-fine region within the shortest time.
However, the use of laser beams makes it very difficult to achieve an ultra-fine focus due to a diffraction limit, thus failing to obtain the practical results for a high-density recording operation.
Thus, an aspect of the present invention provides a heating method using a nanoprobe instead of near-field laser beams.
An aspect of the present invention also provides a scanning probe memory (SPM) that can apply heat to a recording bit of a recording medium by means of a sharp nanoprobe by using a heating method that is applicable to a heat-assisted magnetic recording technology for implementing a high recording density.
According to an aspect of the present invention, there is provided a nanoprobe-based heating apparatus comprising: a nanoprobe having an end formed a tip for applying heat to a magnetic recording bit of a recording medium; a heating unit heating the nanoprobe; a gap control unit controlling a gap between the nanoprobe and the recording medium; and a support unit supporting the nanoprobe, the heating unit, and the gap control unit.
Preferably, the tip is formed sharply, and is located adjacent to or on the top of the magnetic recording bit in a non-contact state with respect to the recording medium to apply heat to the magnetic recording bit.
Preferably, the tip is located adjacent to or on the top of the recording medium to apply heat to the magnetic recording bit.
Preferably, the heating unit includes an electrical resistor heating the nanoprobe.
Preferably, the gap control unit is a piezoelectric device capable of moving finely according to an electrical signal to control the gap.
According to another aspect of the present invention, there is provided a heat-assisted magnetic recording head comprising; a magnetic recording head applying a magnetic field for a magnetic recording on a magnetic recording bit of a recording medium to magnetize the magnetic recording bit; and a nanoprobe-based heating apparatus installed adjacent to the magnetic recording head to apply heat to the magnetized magnetic recording bit of the recording medium.
Preferably, the nanoprobe-based heating apparatus includes: a nanoprobe having an end formed a tip for applying heat to a magnetic recording bit of a recording medium; a heating unit heating the nanoprobe; a gap control unit controlling a gap between the nanoprobe and the recording medium; and a support unit supporting the nanoprobe, the heating unit, and the gap control unit.
Preferably, the heating unit includes an electrical resistor heating the nanoprobe.
Preferably, the gap control unit is a piezoelectric device capable of moving finely according to an electrical signal to control the gap.
Preferably, the tip is formed sharply, and applies heat in a non-contact state with respect to the recording medium.
The above and other aspects, features and other advantages of the present invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which:
Exemplary embodiments of the present invention will now be described in detail with reference to the accompanying drawings.
In the following description of the embodiments of the present invention, a detailed description of well-known functions and configurations incorporated herein will be omitted when it may obscure the subject matter of the present invention.
In the drawings, the thicknesses and sizes of elements are exaggerated for clarity. Like reference numerals refer to like elements throughout.
It will be understood that when an element is referred to as being “connected to” another element, it may be directly connected to the other element or intervening elements may be present.
It will be further understood that the terms “include” and “comprise,” as well as derivatives thereof, when used in this specification, specify the presence of stated elements, but do not preclude the presence or addition of one or more other elements unless otherwise specified.
Referring to
The nanoprobe 24 is installed adjacent to the magnetic recording head 22, and has a tip 25 for applying heat to a magnetic recording bit of the recording medium 21. The heating unit 26 heats the nanoprobe 24, and may be attached on the top of the nanoprobe 25.
The gap control unit 27 controls a gap between the nanoprobe 24 and the recording medium 21, and may be attached on the top of the heating unit 26. The support unit 28 supports the nanoprobe 24, the heating unit 26, and the gap control unit 27, and may be attached to one side of the gap control unit 27.
Specifically, a conventional magnetic recording head and a conventional reproducing head are used as the magnetic recording head 22 and the reproducing head 23, and the sizes and shapes of the magnetic recording head 22 and the reproducing head 23 may vary depending on the performance of a magnetic disk drive.
The nanoprobe 24 and the tip 25 are shaped sharply to heat a fine region, and the tip 25 has a curvature radius of about several nm.
When the heat-assisted magnetic recording head 20 moves in ‘B’ direction, the nanoprobe 24 and the tip 25 are attached in front of the magnetic head 22 and are fixed by the support unit 28.
Also, the tip 25 is located adjacent to or on the top of a recording portion of the recording medium 21 in order to be able to apply sufficient heat for a magnetic recording operation.
The heating unit 26 is implemented using a thermal resistance technique in principle, and may be implemented using other advanced techniques. An electrical resistor for generating resistance heat is connected to the heating unit 26. The electrical resistor is associated with the gap control unit 27 so that a current is prevented from flowing through the electrical resistor in a reproducing or parking mode.
That is, the nanoprobe 24 aims at applying heat to a magnetic recording portion more efficiently, and the gap control unit 27 aims at making the tip 25 and the recording medium 21 maintain a constant gap therebetween in a non-contact state.
Also, since the volume and temperature of the heated portion are closely related with a gap distance between the tip 25 and the recording medium 21, the gap control unit 27 automatically detects the gap distance to control the nanoprobe 24 so that the tip 25 and the recording medium 21 maintain a constant gap therebetween. For automatic control of the gap distance, the gap control unit 27 is formed of piezoelectric material.
Also, the gap control unit 27 is configured to be capable of a fine movement by an electrical signal using the piezoelectric material, and a description of its principle and circuit will be omitted for simplicity.
The support unit 28 serves to support the nanoprobe 24, the tip 25, the heating unit 26, and the gap control unit 27, and does not affect the function and movement of the magnetic recording head 22. Thus, the size and position of the support unit 28 are determined depending on the shape of the magnetic recording head 22 attached thereto, in order to implement the optimal performance.
Thus, the present invention uses the above nanoprobe-based heating apparatus for the heat-assisted magnetic recording head 20, thereby overcoming a superparamagnetism phenomenon, which is the recording limit of a magnetic disk, and thus implementing a high-density recording operation.
Also, since the size (curvature radius) of the tip 25 can be formed finely in a level of several nanometers, the nanoprobe 24 can apply a mechanical scratch, an electric field, heat, or a magnetic field to an ultra-fine region with a diameter of several nm in the recording medium 21 such a disk, thereby enabling a high-density recording/reproducing operation.
Referring to
At this point, the present invention uses the tip 25 of the nanoprobe 24 to apply heat to the magnetized magnetic recording bit 32, thereby making it possible to implement a data recording operation by a weak magnetic field.
A portion to which the heat is applied by the nanoprobe 24 is represented by a circled portion 33, which is an ultra-fine region with a diameter of about 30 nm.
Referring to
Therefore, the tip 25 and the recording medium 21 must maintain an about 30 nm gap distance 42 therebetween. To this end, the gap control unit 27 formed of piezoelectric material automatically controls the gap distance between the tip 25 and the recording medium 21 to be about 30 nm.
As described above, the present invention uses a nanoprobe, which is not limited in size, as a heat source for heat-assisted magnetic recording. Therefore, the present invention can be easily applied to a recording head, a reproducing head, for example, commercialized perpendicular magnetic recording (PMR), pattern media, and the next-generation magnetic recording technology.
Also, the present invention can be easily applied to a conventional recording head, thereby overcoming the limitation of the conventional laser near-field. Also, the present invention can apply sufficient heat to an ultra-fine region of a recording medium in a simpler structure and principle, thereby making it possible to achieve a high recording density of a level of T bit/in2.
Also, the present invention can automatically control a gap between a recording medium and the nanoprobe-based heating apparatus, which is separately installed at a recording/reproducing head, thereby making it possible for the recording medium to maintain a constant temperature.
While the present invention has been shown and described in connection with the exemplary embodiments, it will be apparent to those skilled in the art that modifications and variations can be made without departing from the spirit and scope of the invention as defined by the appended claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10-2007-0122991 | Nov 2007 | KR | national |
| 10-2008-0016793 | Feb 2008 | KR | national |
