US 7,397,639 B2Granted

Magnetic detecting element provided with free layer having layered-ferri configuration

AssigneeTDK Corporation

InventorsTomohiro Yamashita, Naoya Hasegawa, Eiji Umetsu, Ryo Nakabayashi, Akira Takahashi

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Abstract

A magnetic detecting element, which can suppress change in output asymmetry even if the magnetization direction of a pinned magnetic layer is changed 180°, is provided. The magnetic-film-thickness of a second free magnetic layer is increased so as to be greater than that of a first free magnetic layer and offset the torque applied to the second free magnetic layer with that applied to the first free magnetic layer when the sensing current magnetic field occurs. Thus, change in the magnetization direction of the free magnetic layer before and after a sensing current is applied in the magnetic detecting element can be suppressed. The orthogonal state between the free magnetic layer and the pinned magnetic layer is maintained even when a sensing current in the same direction as that before the occurrence is applied in the magnetic detecting element wherein pin inversion occurred, and the output asymmetry is maintained suitably.

A magnetic detecting element having a multi-layer film comprising:

a lower gap layer made up of an insulating material, a seed layer formed on the lower gap layer, a pinned magnetic layer formed directly on the seed layer, a nonmagnetic material layer formed on the pinned magnetic layer, a free magnetic layer formed on the nonmagnetic material layer, and a protective layer formed on the free magnetic layer,
wherein the pinned magnetic layer has a layered-ferri configuration including a first pinned magnetic layer and a second pinned magnetic layer which are made up of a magnetic material and layered with a first nonmagnetic intermediate layer situated therebetween,
the first pinned magnetic layer and the second pinned magnetic layer have positive magnetostriction, and the magnetization direction of each of the first and second pinned magnetic layers is pinned in a uniaxial direction by its uniaxial anisotropy, and
first and second electrode layers are formed on both sides of the multi-layer film so that a sensing current flows in a direction parallel to the film surfaces of the pinned magnetic layer, the nonmagnetic material layer, and the free magnetic layer via the first and second electrode layers, wherein the free magnetic layer has a layered-ferri configuration in which a first free magnetic layer and a second free magnetic layer, which comprise a magnetic material, are layered with a second nonmagnetic intermediate layer situated therebetween, and a magnetic film thickness of the second free magnetic layer in contact with the nonmagnetic material layer is greater than a magnetic film thickness of the first free magnetic layer,
wherein a ratio between the magnetic film thickness of the first free magnetic layer and the magnetic film thickness of the second free magnetic layer (the magnetic film thickness of the first free magnetic layer/the magnetic film thickness of the second free magnetic layer) is between 1/5 and 3/5 inclusive.

2 more elements

Facts

Application

11/194,090Filed 28 Jul 2005

Priority

JP 2004-2297405 Aug 2004

Published

US 2006/0028775 A19 Feb 2006

Granted

8 Jul 2008

Term ends

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Classification8 codes

G01R 33/093
Magnetoresistive devices: using multilayer structures, e.g. giant magnetoresistance sensors
B82Y 10/00
Nanotechnology for information processing, storage or transmission
B82Y 25/00
Nanomagnetism
G11B 5/3903
Using magneto-resistive devices or effects: using magnetic thin film layers or their effects, the films being part of integrated structures

Abstract

Claims12