Dynamic magnetic information storage or retrieval – Head – Magnetoresistive reproducing head
Reexamination Certificate
2002-04-11
2004-03-30
Heinz, A. J. (Department: 2653)
Dynamic magnetic information storage or retrieval
Head
Magnetoresistive reproducing head
Reexamination Certificate
active
06714390
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a giant magnetoresistive effect element and also relates to a magnetoresistive effect type head, a thin-film magnetic memory and a thin-film magnetic sensor, each of which includes this giant magneto-resistive effect element.
2. Description of the Related Art
A so-called merge type combined magnetic head, which results from combining an induction type write magnetic head and a read magnetic head using a magneto-resistive effect (i.e., magneto-resistive effect type head), is employed as a high-density magnetic recording device such as a hard disk drive at present.
As a magneto-resistive effect element (MR element) for use in a magneto-resistive effect type head comprising a read magnetic head located on the lower layer of the combined magnetic head, there has recently been employed a giant magneto-resistive effect element (GMR element) having higher sensitivity.
A GMR element, which is now commercially available on the market, is used in the mode called a “CIP” (Current In Plane) mode in which a sense current for sensing a magneto-resistive effect flows in the direction parallel to a film plane of a lamination layer film of a GMR element.
In the magnetic heads for use as a HDD (hard disk drive), there is the main stream in which a magneto-resistive effect type head including upper and lower shields on the CIP element operable in this CIP mode is used as a read magnetic head of a lower layer.
In order to achieve a recording density higher than 100 gigabits/inch
2
, a magneto-resistive effect element has to have a high linear density so that the magneto-resistive effect element has to be microminiaturized much more.
However, according to the CIP type MR element which is used in the above-mentioned CIP mode, it becomes more difficult to dispose a GMR element between the upper and lower shield films having a film thickness of less than 100 nanometers while the upper and lower shield films and the GMR element are being insulated from each other.
So far it has been examined that a CPP type GMR element, which is used in the mode called a “CPP” (Current Perpendicular to the Plane) in which a sense current flows in the direction perpendicular to a film plane of a lamination layer film of a GMR element and a CPP type TMR (tunneling magneto-resistive effect) element are used as the MR element.
Since the CPP type GMR element uses the shield films as electrodes, the shield films and the GMR element need not be insulated from each other. Hence, the above-mentioned problem of the insulation between the upper and lower shield films and the GMR element can be solved basically.
Further, because the CPP type GMR element has an increased area in which it comes in contact with an electrode film made of a metal film having an excellent thermal conductivity, the CPP type GMR element has a characteristic in which an electromigration is difficult to occur therein at a remarkably high current density as compared with the CIP type GMR element. Therefore, it is considered that the CPP type GMR element is able to realize a narrow magnetic gap and a narrow track width which are the requirements of the high-density recording magnetic head.
When the MR element is used in the magneto-resistive effect type head, the MR element has the upper limit of the resistance value from viewpoints of a thermal noise, an ESD (Electric Static Discharge), a resonance in a read IC and a write IC and so forth. Further, the MR element has the lower limit of the resistance value from a viewpoint of an output.
Then, in the area in which the recording density falls in a range of from 100 to 200 gigabits/inch
2
, when the CPP type TMR element is used as the MR element, the resistance of the MR element has to be decreased. When the CPP type GMR element is used as the MR element, the resistance of the MR element has to be increased.
In order to increase the resistance of the CPP type GMR element, it is proposed that a high resistance layer should be inserted into the lamination layer film of the GMR element, for example.
However, when the high resistance layer is inserted into the lamination layer film of the GMR element as described above, if a hard magnetic material having a conductivity, such as a metal is used as a hard film (hard magnetic film) to stabilize the magnetization of the GMR element, then a sense current is shunted into the hard film so that a current, which is flowing through the GMR element, is decreased. There then arises a problem that the output of the GMR element is lowered.
For this reason, in order to insulate the GMR element and the hard film from each other, there can be considered a configuration in which a GMR element and a hard film are bonded to each other through an insulating material or a configuration in which an insulating or high-resistance hard magnetic material is used as a hard film.
However, from a view point of the cost of a material, it is to be desired that a hard magnetic material having a conductivity, which can be manufactured comparatively inexpensively, should be used as a hard film. Furthermore, in order to sufficiently stabilize a magnetization of a magnetization free layer of a GMR element, it is to be desired that the hard film should directly be bonded to the GMR element.
SUMMARY OF THE INVENTION
In view of the aforesaid aspect, it is an object of the present invention to provide a giant magneto-resistive effect element capable of producing a high output and a high resistance and which can cope with a high recording density and a magneto-resistive effect type head, a thin-film magnetic memory and a thin-film magnetic sensor, each of which includes this giant magneto-resistive effect element.
According to an aspect of the present invention, there is provided a giant magneto-resistive effect element comprising a lamination layer film including a ferromagnetic film, a nonmagnetic film and an antiferromagnetic film and in which the ferromagnetic film includes a magnetization free layer and a magnetization fixed layer and a current is restricted by an upper electrode and a lower electrode so that the current flows to the direction perpendicular to the film plane of the lamination layer film, wherein the lamination layer film is laminated including a high-resistance layer, a hard magnetic film made of a conductive hard magnetic material and an insulating layer are directly bonded to respective outsides of the lamination layer film along its width direction and the hard magnetic film is shifted from the high-resistance layer and bonded nearer the magnetization free layer.
According to another aspect of the present invention, there is provided a magneto-resistive effect type head including a giant magneto-resistive effect element comprising a lamination layer film including a ferromagnetic film, a nonmagnetic film and an antiferromagnetic film, the ferromagnetic film includes a magnetization free layer and a magnetization fixed layer and a current is restricted by an upper electrode and a lower electrode so that the current flows to the direction perpendicular to the film plane of the lamination layer film, the lamination layer film is laminated including a high-resistance layer, a hard magnetic film made of a conductive hard magnetic material and an insulating layer are directly bonded to respective outsides of the lamination layer film along its width direction and the hard magnetic film is shifted from the high-resistance layer and bonded nearer the magnetization free layer, wherein upper and lower magnetic shields are disposed so as to sandwich the giant magneto-resistive effect element through a gap film made of a nonmagnetic conductive material, the gap film and the magnetic shields constitute the upper electrode and the lower electrode and the upper electrode, the lower electrode and the lamination layer film are connected to each other electrically.
In accordance with further another aspect of the present invention, there is provided a thin-film magnetic memory including a bit line, a word line a
Matsuzono Atsushi
Ono Hiroaki
Terada Shoji
Heinz A. J.
Sonnenschein Nath & Rosenthal LLP
Sony Corporation
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