Fujitsu Corporation

University of Alabama

Keiichi Nagasaka

Yutaka Shimizu

Atsushi Tanaka

Yoshihiko Seyama

Hitoshi Kishi

Hirotaka Oshima

Hitoshi Kanai

Reiko Kondo

Shin Eguchi

Junya Ikeda

Tong Zhao

Hideo Fujiwara

Takahiko Sugawara

William Hill Butler

Arata Jogo

Julian Velev

Amrit Bandyopadhyay

A CPP spin-valve element formed on a substrate including a free layer structure including at least one ferromagnetic layer and a pinned layer structure including at least one ferromagnetic layer. The free layer is magnetically softer than the pinned layer. A thin non-magnetic spacer layer structure configured to separate the free layer and the pinned layer is provided in order to prevent a magnetic coupling between the free and pinned layer structures, and to allow an electric current to go there through. At least two current-confining (CC) layer structures including at least two parts having significantly different current conductivities are incorporated therein.

CPP spin-valve element

A magnetoresistive element of a CPP type configuration including a fixed magnetic layer, a first non-magnetic layer, a free magnetic layer, and a second non-magnetic layer is disclosed. The magnetoresistive element includes a first interface layer situated between the free magnetic layer and the first non-magnetic layer, and a second interface layer situated between the free magnetic layer and the second non-magnetic layer. The first interface layer and the second interface layer include a material mainly having CoNiFe.

Magnetoresistive element having current-perpendicular-to-plane structure, magnetic head, and magnetic memory apparatus thereof

A magnetoresistive element is disclosed that includes a magnetoresistive film; a cap film configured to cover the magnetoresistive film and include a three-layer structure in at least a part thereof, the three-layer structure being formed of a third protection layer, a second protection layer, and a first protection layer in order from the magnetoresistive film side; and upper and lower terminals for applying a sense current perpendicularly to the surface of the magnetoresistive film. The magnetoresistive film includes a first magnetic layer whose direction of magnetization is changed by an external magnetic field, a second magnetic layer whose direction of magnetization is fixed with respect to the external magnetic field, and a nonmagnetic layer magnetically separating the first magnetic layer and the second magnetic layer.

Magnetoresistive element and method of manufacturing the same

A CPP magnetoresistive effect element includes a free magnetization layer, a fixed magnetization layer, and a plurality of conductive non-magnetic intermediate layers formed between the free magnetization layer and the fixed magnetization layer. An insulating layer and a magnetic layer including magnetic atoms are provided between any two of the non-magnetic intermediate layers.

CPP magnetoresistive effect element and magnetic storage device having a CPP magnetoresistive effect element

The magnetoresistive effect element comprises an electrode layerof a crystalline material; a base layerof a conductive amorphous material formed over the electrode layer, an antiferromagnetic layerof a crystalline material formed over the base layer, a ferromagnetic layerformed over the antiferromagnetic layerand having the magnetization direction defined by the antiferromagnetic layer, a nonmagnetic intermediate layerformed over the ferromagnetic layer, a ferromagnetic layerformed over the nonmagnetic intermediate layerand having the magnetization direction changed by an external magnetic field, and an electrode layerformed over the ferromagnetic layer

Magnetoresistive effect having multiple base layers between an electrode and an antiferromagnetic layer, magnetic head, and magnetic recording device

A magnetoresistive element that detects a change of magnetoresistance by giving a sense current in the thickness direction of a magnetoresistive effect film including at least a base layer, a free layer, a non-magnetic layer, a pinned layer, a pinning layer, and a protection layer, includes a granular structure layer that includes conductive particles and an insulating matrix material in the form of a thin film containing the conductive particles in a dispersed state and having a smaller thickness than the particle diameter of the conductive particles, the granular structure layer being interposed between at least two adjacent layers among the base layer, the free layer, the non-magnetic layer, the pinned layer, the pinning layer, and the protection layer.

Magnetoresistive element

A smaller electrode layer of an upper electrode is formed on a surface of a free magnetic layer. A domain controlling film of an insulating material is formed adjacent to the smaller electrode layer on the surface of the free magnetic layer. Magnetization of the free magnetic layer is oriented in a single direction based on magnetic exchange coupling between the domain controlling film and the free magnetic layer. An electric connection is established between the free magnetic layer and the upper electrode only through the smaller electrode layer. The path of a sensing current can be reduced in the free and a pinned magnetic layer. A higher sensitivity can thus be obtained in the CPP structure magnetoresistive element. Effective magnetic core width can also be reduced in the CPP structure magnetoresistive element.

Magnetoresistive element having current-perpendicular-to-the-plane structure and having improved magnetic domain control

A magnetoresistive sensor including the following layers, in order: a first conductor layer; a first antiferromagnetic layer; a first pinned ferromagnetic layer; a first nonmagnetic intermediate layer; a free ferromagnetic layer; a second nonmagnetic intermediate layer; a second pinned ferromagnetic layer; a second antiferromagnetic layer; and a second conductor layer. Alternatively, the magnetoresistive sensor may include the following layers, in order: a first conductor layer; a first free ferromagnetic layer; a first nonmagnetic intermediate layer; a first pinned ferromagnetic layer; an antiferromagnetic layer; a second pinned ferromagnetic layer; a second nonmagnetic intermediate layer; a second free ferromagnetic layer; and a second conductor layer.

Magnetoresistive sensor

Disclosed herein is a spin valve magnetoresistive sensor including a first conductor layer, a free ferromagnetic layer provided on the first conductor layer, a nonmagnetic intermediate layer provided on the free ferromagnetic layer, a pinned ferromagnetic layer provided on the nonmagnetic intermediate layer, an antiferromagnetic layer provided on the pinned ferromagnetic layer, and a second conductor layer provided on the antiferromagnetic layer. At least one of the free ferromagnetic layer and the pinned ferromagnetic layer has a thickness larger than that providing a maximum resistance change rate or resistance change amount in the case of passing a current in an in-plane direction of the at least one layer. That is, the thickness of at least one of the free ferromagnetic layer and the pinned ferromagnetic layer falls in the range of 3 nm to 12 nm.

Spin valve magnetoresistive sensor having CPP structure

A magnetoresistive device includes a laminated film, and a mechanism for applying sense current in a direction of lamination in the laminated film, wherein the laminated film includes a first ferromagnetic layer having a substantially fixed direction of magnetization, a second ferromagnetic layer having a freely variable direction of magnetization according to an external magnetic field, the second ferromagnetic layer including a non-magnetic metal layer, and two or more ferromagnetic metal layers separated from each other by the non-magnetic metal layer in the direction of lamination, and a non-magnetic intermediate layer that separates the first and second ferromagnetic layer from each other.

CPP GMR free layer having ferromagnetic layers with parallel magnetization separated by non-magnetic layer

A magnetic sensor having such a structure that a hard layer for controlling the magnetic domain formed of a conductive hard magnetic material, and a magnetic sensor layer, are at least partially in direct contact with each other, and current flows in the direction wherein at least a main component of current is perpendicular to the surface of the magnetic sensor layer. The current flowing in the magnetic sensor layer and the hard layer is controlled by changing the resistivity of the hard layer. The magnetic sensor is used as a magnetic read head in a magnetic recording apparatus such as magnetic disk apparatus.

Magnetic sensor, magnetic head and magnetic recording apparatus

A current perpendicular-to-the-plane (CPP) structure spin valve magnetoresistive (MR) transducer includes an insulating layer. A pinned or free ferromagnetic layer serves to space or isolate the insulating layer from a non-magnetic spacer layer interposed between the pinned and free ferromagnetic layers. The sensing current is allowed to penetrate through the insulating layer. Fine pin-holes generally formed in the insulating layer are supposed to enable migration of electrons through the insulating layer. Similar to the situation in which the sensing current is allowed to flow through a reduced sectional area, a larger variation can be obtained in response to the inversion of the magnetization in the free ferromagnetic layer. The spin valve MR transducer is expected to greatly contribute to realization of a still higher recording density. Moreover, the spin valve MR transducer is also expected to exhibit an electric resistance approximately equal to a tenth part of that of a well-known tunnel junction magnetoresistive (TMR) element. Accordingly, a thermal noise can significantly be suppressed in the spin valve MR transducer as compared with the TMR element.

Current perpendicular-to-the-plane structure spin valve magnetoresistive head

A spin-valve magnetoresistive device that can reproduce a signal magnetic field from a magnetic recording medium with high precision is provided. This spin-valve magnetoresistive device includes a free magnetic layer (a first ferromagnetic layer), a non-magnetic conductive layer, a multi-layered fixed magnetic layer, and an anti-ferromagnetic layer. These layers are laminated in that order. The multi-layered fixed magnetic layer includes a second ferromagnetic layer, a reverse parallel coupling intermediate layer, and a third ferromagnetic layer, which layers are laminated in that order. A fourth ferromagnetic layer that cancels a leakage magnetic field generated from the multi-layered fixed magnetic layer is disposed in contact with the anti-ferromagnetic layer.

Spin-valve magnetoresistive device having a layer for canceling a leakage magnetic field

A method is disclosed for magnetizing a magnetic system including a ferromagnetic layer magnetized in a first direction and an anti-ferromagnetic layer provided on said ferromagnetic layer in exchange coupling therewith. The method includes a first thermal annealing process including the sub-steps of annealing the magnetic system in a first annealing state, and applying a magnetic field to the magnetic system in a second direction different from the first direction, while maintaining the magnetic system in the first annealing state. A second thermal annealing process includes the sub-steps of annealing the magnetic system after the first thermal annealing process, to a second annealing state, and applying a magnetic field in a third direction different from the second direction while maintaining the magnetic system in the second annealing state.

Spin-valve magnetic head with the pinned layer having different directions for its magnetization axis and its easy axis

A method is disclosed for fabricating a spin-valve magnetic head including a layered body of a first ferromagnetic layer having a first easy axis of magnetization extending in a first direction, a non-magnetic layer formed on the first ferromagnetic layer, a second ferromagnetic layer provided on the non-magnetic layer, and an anti-ferromagnetic layer provided on the second ferromagnetic layer in exchange coupling therewith. The method includes a first thermal annealing process with the steps of annealing the layered body in a first annealing state and applying a magnetic field to the layered body in a second direction different from the first direction, while maintaining the layered body in the first annealing state. The method further includes a second thermal annealing process with the steps of annealing the layered body, after the first thermal annealing process, in a second annealing state and applying a magnetic field in a third direction different from the second direction while maintaining the layered body in the second annealing state.

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Kawasaki, Japan

Keiichi Nagasaka