JPS63259813A - Thin film magnetic head - Google Patents

Abstract

PURPOSE:To enable efficient reproduction by using a ceramics superconductor to form a nonmagnetic material of a ring type magnetic head forming a magnetic gap. CONSTITUTION:A magnetic core 2 which consists of a ferromagnetic material such as Co, Nb and Zr and is sandwiched by a ceramics base material 1 is joined by gap surfaces. The superconductor 3 consisting of Y-Ba-Cu-O is formed to 0.3mum thickness in the front part gap facing a recording medium and is adhered by low melting point glass 4 of 0.05mum thickness formed in the gap part between the front part and the rear part. A winding window 5 is provided. The Y-Ba-Cu-O of the gap material attains a superconducting state and the infiltration of magnetic fluxes therein is prevented by a Meissner effect under the magnetic field of <=1 lower critical Hc when this head is cooled down to <=80 deg.K. The magnetic field in the gap generated by the recording medium at the time of reproduction is extremely small and does not, therefore, exceed the lower critical magnetic field. Since the superconducting state is maintained, the magnetic fluxes leaking in the gap are eliminated.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a magnetic head having highly efficient reproduction characteristics even with a narrow gap.

2. Description of the Related Art Ring-shaped magnetic heads are widely used for recording and reproducing signals on magnetic recording media. FIG. 3 shows the structure of a ring-type magnetic head. A magnetic core 22 made of a ferromagnetic material such as CoNbZr is sandwiched between ceramic substrates 21 and joined at a gap surface. As the gap material 23, a non-magnetic material such as glass or S i 02 is used. 24 is a winding window.

In a ring-type magnetic head, in order to prevent a drop in efficiency due to gap loss during reproduction, as the recording density increases and the recording wavelength becomes shorter (as the recording wavelength becomes shorter), the gap length G must be decreased. As the magnetic resistance of the coil decreases, the leakage of magnetic flux in the gap increases, and the magnetic flux linking the coil decreases, resulting in a decrease in head efficiency.For this reason, a metal such as Cu is used as the gap material. Attempts have been proposed to prevent the decrease in efficiency by blocking magnetic flux leaking through the gap using eddy currents.

Problems to be Solved by the Invention Even if metal is used as the gap material, the magnitude of eddy current is limited by the resistance of the metal, so it is not effective enough to sufficiently prevent leakage of magnetic flux during the gap and increase efficiency. I can't get it. Furthermore, when metal is used as the gap material, the gear and knobs are particularly likely to wear due to sliding with the recording medium, causing uneven wear that creates steps, which causes the magnetic core to collapse and the gear and knobs to widen. also happens.

In particular, in thin-film magnetic heads, the cross-sectional area of the magnetic core is smaller and the magnetic resistance of the magnetic path is greater than in bulk-type heads, so the reduction in efficiency due to the narrowing of the gap is significant.

Means for Solving the Problems In a ring-shaped magnetic head comprising a magnetic core made of a ferromagnetic material, a coil interlinked with the magnetic core, and a non-magnetic material forming a magnetic gap, at least the non-magnetic material is made of ceramic. It is composed of a system superconductor.

Function According to the present invention, since the magnetic gap is made of a superconductor, the Meissner effect, which becomes completely diamagnetic in the superconducting state, eliminates magnetic flux leaking into the gears and hubs during playback, and causes no magnetic flux to enter the magnetic gap. Most of the reproduced magnetic flux passes through the magnetic core and interlinks with the coil. Therefore, even if the magnetic gap length is reduced for short wavelength reproduction, the reproduction efficiency does not decrease.

In addition, since a ceramic material is used as the superconductor, it has sufficient hardness compared to the case of using a metal superconductor such as Nb, so that only the gap material is worn out when it slides against the recording medium. , there is no problem of the magnetic core near the gap collapsing and the cap length increasing, and stable performance can be obtained.

Embodiment A first embodiment of the present invention will be described with reference to FIG. FIG. 1 is a perspective view showing a head of the present invention, in which a magnetic core 2 made of a ferromagnetic material such as CoNbZr is sandwiched between ceramic substrates 1 and joined at a gap surface. A 0.3 μm thick superconductor 3 made of Y-Ba-Cu-0 is formed in the front gap facing the recording medium, and a 0.05 μm thick low melting point superconductor 3 is formed in the front and rear gap portions. It is bonded by glass 4. 5 is a winding window. When this head is cooled to below 80°C, the Y-Ba-Cu-0 used as the gap material becomes superconducting, and magnetic flux does not enter into it due to the Meissner effect for magnetic fields below the lower critical magnetic field Hcl. . During reproduction, the magnetic field in the gap generated by the recording medium is so small that it does not exceed the lower critical magnetic field and the superconducting state is maintained, so that no magnetic flux leaks through the gap. For example, track width 4
0μm, gap length 0.3μm, gap depth 25μm
The regeneration efficiency of this head is about 0.6, assuming the magnetic permeability of the magnetic core as 1000, but this becomes close to 1, and the output is improved by about 1.6 times. During recording, under conditions where the coercive force of the medium is small and recording is possible with a magnetic field in the gap that is less than the lower critical magnetic field of the gap material, the magnetic flux generated by the recording current does not flow through the gap due to the Meissner effect, and all of it exits the gap as a recording magnetic field. , efficient recording is possible with a small recording current. In addition, since a ceramic superconducting material is used as the gap material, there is little difference in hardness between the substrate and the magnetic core, which prevents uneven wear due to sliding with the recording medium and widening of the gap due to collapse of the core material near the gap. Hard to occur.

A second embodiment of the present invention will be explained based on FIG. 2. FIG. 2 shows a cross-sectional view of the thin film head of the present invention, in which a magnetic core 12 made of sendust, permalloy, etc. is formed on a ceramic substrate 11, and on top of that a magnetic core 12 made of a material such as Sendust or Permalloy is placed on a ceramic substrate 11. Superconductor 13 such as Cu-0
is formed. Furthermore, a coil 14 made of AI or Cu is formed thereon via a non-magnetic insulating material 15 such as SiO2. Furthermore, a ferromagnetic thin film serving as the other magnetic core 16 is bonded to the magnetic core 11 at the rear gap portion 17 thereon. If the gap material is non-magnetic,
Even if the gap material extends to the rear gap part 17, there is almost no problem with magnetic resistance as long as the area of the rear gap part is large, but when using a superconductor, if the material extends to the rear gap part, the flow of magnetic flux is blocked and there is a problem. It is necessary to remove the rear gap, which causes a significant decrease in efficiency.Most of the leakage magnetic flux that does not link the coil passes through the magnetic gap, but some leakage also occurs between the magnetic cores surrounding the coil. Therefore, it is clear that regeneration efficiency will be better if the superconductor that forms the magnetic gap is formed over the entire overlap between the coil and the magnetic core.Also, if there is no leakage of magnetic flux in the gap, Even if the gap depth is large, there is little decrease in efficiency, so a head with a long service life against wear can be realized.

Effects of the Invention According to the present invention, by using a ceramic superconducting material as the cap material, there is no leakage of magnetic flux in the magnetic gap during reproduction, so the reproduction efficiency is close to 1 (which means highly efficient reproduction). Also, since uneven wear and gap collapse are less likely to occur, stable characteristics can be maintained for a long time.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of a magnetic head according to a first embodiment of the present invention, FIG. 2 is a sectional view of a magnetic head according to a second embodiment of the present invention, and FIG. 3 is a conventional magnetic head. FIG. 1... Substrate, 2... Magnetic core, 3... Superconductor,
4...Glass, 5...Wound window. Name of agent: Patent attorney Toshio Nakao (1 person) Figure 1 Figure 2 Figure 3

Claims (2)

[Claims] (1) In a ring-shaped magnetic head consisting of a magnetic core made of a ferromagnetic material, a coil interlinked with the magnetic core, and a nonmagnetic material forming a magnetic gap, at least the nonmagnetic material is made of a ceramic superconductor. A thin film magnetic head characterized by: (2) The magnetism according to claim 1, characterized in that the ceramic superconductor forming the magnetic gap extends over the entire overlapping portion of the magnetic core and the coil, excluding the joint of the magnetic core. head.