Electrical resistors – Resistance value responsive to a condition – Magnetic field or compass
Patent
1999-03-18
2000-08-15
Easthom, Karl
Electrical resistors
Resistance value responsive to a condition
Magnetic field or compass
360113, H01L 4306
Patent
active
061042757
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a magnetoresistive element, more particularly to en element which exhibits a so-called, giant magnetoresistive effect.
BACKGROUND ART
A magnetoresistive element (MR element) is an element which detects magnetic field changes on the basis of a magnetoresistive effect that produces changes in electrical resistance as a magnetic field varies. For a high detection sensitivity of such a magnetoresistive element, its application to reproduce heads for magnetic recording media, such as a hard disc, has been expected. However, technology has shown the continuous growth of recording density in hard discs. For application of the magnetoresistive element to reproduce heads for further improved high density recording media, it will likely need to exhibit a still higher sensitivity. If the magnetoresistive element is to increase in sensitivity, its MR ratio must be raised. In the attempt to obtain a magnetoresistive element exhibiting a high MR ratio, a giant magnetoresistive element (GMR element) has been investigated which utilizes a magnetoresistive film having a multilayer structure consisting of a ferromagnetic layer and a nonmagnetic conductive layer. As a result, a variety of GMR element designs has been proposed heretofore. Known GMR element designs include, for example, a coercivity differential type GMR element of a structure having a nonmagnetic conductive layer interposed between a pair of ferromagnetic layers having different coercive forces; a spin-valve type GMR element having a nonmagnetic conductive layer interposed between a pair of ferromagnetic layers one of which pins an antiferromagnetic layer thereon; and an artificial lattice type GMR element consisting of ferromagnetic layers and nonmagnetic conductive layers repeatedly stacked in plural periodic sequences.
However, in order to achieve a further improvement in recording density, GMR elements need to have further higher MR ratios. The development of GMR elements which permit the use of a narrow track width has been also demanded.
An object of the present invention is directed toward meeting the needs as sought heretofore and resides in its provision of a novel structure of a magnetoresistive element which can exhibit a higher MR ratio than conventional.
DISCLOSURE OF THE INVENTION
A magnetoresistive element of the present invention is characterized as including a multilayer film having a multilayer structure in which a nonmagnetic conductive layer is interposed between a pair of ferromagnetic layers, a pair of electrodes for producing a detection current flow through the multilayer film, and a filter layer of ferromagnetic material interposed between a positive one of the pair of electrodes and one of the pair of ferromagnetic layers for delivering spin-polarized electrons to the ferromagnetic layer, and is characterized that a traveling distance of electrons in the ferromagnetic layer is shorter than a spin diffusion length.
In the present invention, the spin diffusion length refers to an average distance the spin-polarized electrons can travel diffusively. In the present invention, since the traveling distance of electrons in the ferromagnetic layer, to which the spin-polarized electrons are delivered, is maintained shorter than the spin diffusion length, the electrons in the ferromagnetic layer is moveable while in a spin polarization state.
Also in the present invention, between the pair of electrodes, the positive electrode refers to an electrode from which electrons flow. The present invention requires that one filter layer be minimally provided between the positive electrode and the ferromagnetic layer on a positive side. In a more preferred embodiment, an additional filter layer may be provided between a negative electrode and the ferromagnetic layer on a negative side.
The following explains a principle on the basis of which a magnetoresistive element of the present invention exhibits a higher MR ratio than conventional magneto-resistive elements.
FIG. 1 is a sectional view, showin
REFERENCES:
patent: 4639806 (1987-01-01), Kira et al.
patent: 4800457 (1989-01-01), Kryder et al.
patent: 5206590 (1993-04-01), Dieny et al.
patent: 5357388 (1994-10-01), Smith
patent: 5654566 (1997-08-01), Johnson
patent: 5876843 (1999-03-01), Ishiwata
patent: 5910869 (1999-06-01), Fedeli
"Physical Priciples of the Bipolar Spin Transistor," Mark Johnson, Naval Research Lab., vol. 19, No. 3, 1995, pp. 684-691.
Easthom Karl
Sanyo Electric Co,. Ltd.
LandOfFree
Magnetoresistive element does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Magnetoresistive element, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Magnetoresistive element will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2011259