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US 6,807,034 B2Granted
Dual spin-valve CCP type thin-film magnetic element with multi free layers
AssigneeAlps Electric Co., Ltd.
InventorsNaoya Hasegawa, Eiji Umetsu
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Abstract
In a CPP-type magnetic sensing element, a free magnetic layer includes at least two magnetic sublayers and an intermediate sublayer placed between the two adjacent magnetic sublayers, and thus the free magnetic layer is in a synthetic ferrimagnetic state. Since the physical thickness of the free magnetic layer can be increased and the resultant magnetic moment can be decreased, the bulk scattering effect is satisfactorily displayed and the magnetization of the free magnetic layer varies satisfactorily in response to en external magnetic field, resulting in an increase in the read output.
Claims29
A magnetic sensing element comprising a multilayer film comprising:
- a free magnetic layer;
- an upper nonmagnetic interlayer placed on the free magnetic layer;
- a lower nonmagnetic interlayer placed under the free magnetic layer;
- an upper pinned magnetic layer placed on the upper nonmagnetic interlayer;
- a lower pinned magnetic layer placed under the lower nonmagnetic interlayer;
- an upper antiferromagnetic layer placed on the upper pinned magnetic layer;
- and
- a lower antiferromagnetic layer placed under the lower pinned magnetic layer, each of the upper antiferromagnetic layer and the lower antiferromagnetic layer pinning a magnetization direction of each of the upper pinned magnetic layer and the lower pinned magnetic layer in a predetermined direction by an exchange coupling magnetic field,
- wherein a current flows perpendicular to planes of the individual layers of the multilayer film;
- the free magnetic layer comprises at least two magnetic sublayers and an intermediate sublayer placed between the two magnetic sublayers;
- each of the upper pinned magnetic layer and the lower pinned magnetic layer comprises two magnetic sublayers and an intermediate sublayer placed therebetween;
- in the lower pinned magnetic layer, a magnetic moment of the magnetic sublayer in contact with the lower nonmagnetic interlayer is larger than a-magnetic moment of the magnetic sublayer in contact with the lower antiferromagnetic layer;
- and in the upper pinned magnetic layer, a magnetic moment of the magnetic sublayer in contact with the upper nonmagnetic interlayer is larger than a magnetic moment of the magnetic sublayer in contact with the upper antiferromagnetic layer.
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A magnetic sensing element comprising:
- at least two multilayer films, each multilayer film comprising a free magnetic layer, an upper nonmagnetic interlayer placed on the free magnetic layer, a lower nonmagnetic interlayer placed under the free magnetic layer, an upper pinned magnetic layer placed on the upper nonmagnetic interlayer, and a lower pinned magnetic layer placed under the lower nonmagnetic interlayer;
- an intermediate antiferromagnetic layer placed between the two multilayer films;
- a lower antiferromagnetic layer placed under a lower surface of the multilayer film located at a bottom of the magnetic sensing element;
- and
- an upper antiferromagnetic layer placed on an upper surface of the multilayer film located on a top of the magnetic sensing element,
- wherein a magnetization direction of each of the upper pinned magnetic layer and the lower pinned magnetic layer is pinned in a predetermined direction by an exchange coupling magnetic field generated between the pinned magnetic layer and any one of the intermediate antiferromagnetic layer, the lower antiferromagnetic layer, and the upper antiferromagnetic layer, and a current flows perpendicular to planes of the individual layers each of the upper pinned magnetic layer and the lower pinned magnetic layer comprises two magnetic sublayers and an intermediate sublayer placed therebetween;
- in the lower pinned magnetic layer, a magnetic moment of the magnetic sublayer in contact with the lower nonmagnetic interlayer is larger than a magnetic moment of the magnetic sublayer in contact with the lower antiferromagnetic layer;
- and in the upper pinned magnetic layer, a magnetic moment of the magnetic sublayer in contact with the upper nonmagnetic interlayer is larger than a magnetic moment of the magnetic sublayer in contact with the upper antiferromagnetic layer.
5 more elements
Dependencies are inferred from the claim text.