Hitachi Metals, Ltd.

Applied Magnetics, LLC

Chiharu Mitsumata

Toshio Kobayashi

Yasuyuki Okada

Masahiro Mita

Ryo Goto

Shin Noguchi

Hirokazu Araki

Hisao Kurosawa

Masanobu Yamazaki

Kyohei Aimuta

Masahiro Tobise

Simon H Liao

Chyu Jiuh Torng

Tetsurou Kawai

Hisayuki Miura

A rotation-angle-detecting apparatus comprising a magnet rotor, a magnetic sensor detecting the direction of magnetic flux from the magnet rotor, a correction circuit, and an angle-calculating circuit, the magnetic sensor having bridge circuits X and Y each comprising four connected magnetoresistive devices, each magnetoresistive device comprising a spin-valve, giant-magnetoresistive film, the correction circuit calculating difference (Vx&#x2212;Vy) and sum (Vx+Vy) from the output voltage Vx of the bridge circuit X and the output voltage Vy of the bridge circuit Y, and making their amplitudes equal to each other, and the angle-calculating circuit determining the rotation angle of the rotor by arctangent calculation from a signal (Vx&#x2212;Vy)' and a signal (Vx+Vy)&#x2032; supplied with the same amplitude from the correction circuit.

Rotation-angle-detecting apparatus

A magnetic sensor comprising a bridge circuit in which four magnetoresistive devices are connected, the magnetoresistive device comprising a spin-valve, giant-magnetoresistive film comprising a pinned layer having unidirectional magnetic anisotropy, a free layer whose magnetization direction is rotated in alignment with an external magnetic field direction, and an intermediate layer sandwiched by the pinned layer and the free layer, and at least one of the magnetoresistive devices meeting the condition of 36&#xb0;&#x2266;&#x3b8;&#x3c;45&#xb0;, wherein &#x3b8; is an acute angle between its longitudinal direction and the magnetization direction of the pinned layer.

Magnetic sensor and rotation-angle-detecting apparatus with a bridge circuit

A magnetic sensor-type antenna comprising a magnetic core and a coil wound around the magnetic core for receiving electromagnetic waves, which is disposed in a housing such that the end portion of the magnetic core is bent away from the housing or a metal portion of the housing, and a timepiece, a keyless entry system and an RFID system each comprising such an antenna.

Antenna, and radio timepiece using the same, keyless entry system, and RFID system

An antenna comprising a magnetic main-path member comprising a coil wound around a magnetic core, and a magnetic sub-path member magnetically connected to the magnetic core for constituting a substantially closed magnetic path with the magnetic main-path member, the antenna meeting the relation of (S/N)&#x3e;(S/N), wherein (S/N)is a ratio of a signal voltage S obtained from the coil to a noise voltage N in this antenna, and (S/N)is a ratio of a signal voltage S to a noise voltage N in an antenna having the same structure except for having no magnetic sub-path member.

Antenna, and radio-controlled timepiece, keyless entry system and RFID system

A magnetoresistive (MR) sensor for MR heads comprising a magnetoresistive ferromagnetic layer (MR layer) and an antiferromagnetic layer in direct contact with the surface of the MR layer. The MR layer has a face-centered-cubic (fcc) structure. The crystalline structure of the antiferromagnetic layer is the fcc structure in the vicinity of the interface of the MR layer and the antiferromagnetic layer, and continuously changes to a face-centered-tetragonal (fct) structure toward the surface opposite to the interface. The interface of the MR layer and the antiferromagnetic layer is continuous with respect to the crystalline structure due to the epitaxial growth of the antiferromagnetic layer on the surface of the MR layer.

Magnetoresistive sensor

Method of producing magnetoresistive sensor

A magnetoresistive (MR) transducer is disclosed in which an exchange coupled anisotropy field is provided by an antiferromagnetic NiMn alloy in contact with the MR alloy. Improved exchange coupling is achieved using an MR layer and adjacent NiMn exchange coupling layer which have substantially fcc structure and a preferred {111} crystalline orientation. The exchange bias field is observed to correlate strongly with the structural order of the films. A preferred method of fabricating the MR transducer enhances the structural order of the layers during growth, thereby reducing a post-deposition anneal typically required in such processes. The preferred fabrication process further provides greater predictability and control over the resulting exchange coupling.

Exchange biased magnetoresistive transducer

A magnetoresistive (MR) head for sensing magnetic data recorded on a magnetic recording medium with high track density and high linear density includes a magnetoresistive conductive layer (MR layer), a soft magnetic layer (SAL) for transversely biasing the MR layer and hard magnet layers for longitudinally biasing and controlling magnetization in the central sensing regions of the MR layer and the SAL. The longitudinal bias applied to the SAL is less than that to the MR layer so that a sensing current produces an effective magnetic field to saturate the SAL transversely. So, magnetization in the MR layer is kept at an angle of 40 to 45 degrees to easy magnetization direction of the MR layer and the improved reproducing output is obtained.

Magnetoresistive head with hard magnetic bias

An SAL-type magnetoresistive playback head that is highly sensitive and that limits Barkhausen noise is provided by optimizing the magnetic properties of the permanent magnet film. On top of a lower insulating layer are stacked a soft magnetic bias film (SAL film), a magnetic separating film (shunt film), a magnetoresistive film (MR film), and an upper insulating layer, in that order. The outer sides of the track of the MR film are in direct contact with the permanent magnet film or in indirect contact via a base film. Alternatively, the present invention relates to a spin-valve magnetoresistive playback head. On top of a lower insulating layer are stacked an anti-ferromagnetic film, a fixed magnetizing film, a magnetic separating film, a movable magnetizing film (MR film), and an upper insulating layer, in that order. The outer sides of the track of the movable magnetizing film are in direct contact with the permanent magnet film or in indirect contact via a base film. In either type of playback head, Barkhausen noise is eliminated by using a CoCrPt alloy film having a composition that provides the magnetic properties needed for a permanent magnet film that can handle narrow tracks and narrow gaps, and by specifying a ratio between the thicknesses of the MR film and the permanent magnet film.

Magnetoresistive playback head

In a floating magnetic head, noises produced at the time of reproduction are reduced, thereby enhancing the precision of detection of a track position. The floating magnetic head uses a monocrystal magnetic material constituting an electromagnetic transducer element, and a crystal orientation of the monocrystal magnetic material in the electromagnetic transducer element is parallel to a direction of travel of a medium. In the case of .vertline..lambda..sub.111 .vertline.+2.times.10.sup.-6 .ltoreq..vertline..lambda..sub.100 .vertline., the crystal orientation is in the range of a solid angle of 3.multidot.sin.theta..multidot.cos.phi. which satisfies 0.ltoreq..theta.&lt;10 degrees and 0.ltoreq..phi..ltoreq.360 degrees around [111], and in the case of .vertline..lambda..sub.111 .vertline..gtoreq..vertline..lambda..sub.100 .vertline.+2.times.10.sup.-6, the crystal orientation is in the range of a solid angle of sin .theta..multidot.cos.phi. which satisfies 0.ltoreq..theta.&lt;10 degrees and 0.ltoreq..phi..ltoreq.360 degrees around [100], where .lambda..sub.111 and .lambda..sub.100 respectively represent linear magnetostriction constant of the monocrystal magnetic material in directions &lt;111&gt; and &lt;100&gt;. The monocrystal magnetic material is a monocrystal MnZn ferrite whose chemical composition is represented by 20.ltoreq.MnO.ltoreq.40, 10.ltoreq.ZnO.ltoreq.25 50.ltoreq.Fe.sub.2 O.sub.3 .ltoreq.65 in terms of mol. %.

Floating magnetic head with reduced magnetostriction vibration noise

A flying-type magnetic head includes a magnetic head chip composed of a pair of cores, each having a metallic magnetic thin film thereon which faces a magnetic gap. The magnetic chip is inserted and fixed in a slit provided in a non-magnetic slider at the outlet side of a magnetic recording medium generating airflow across an air bearing. The back of the slider is fixed to a gimbal in such a manner that a flying plane portion of the magnetic head faces the magnetic recording medium. The height at the flying plane portion of the slider is structurally controlled such that the height where the back of the slider is fixed to the gimbal differs by 20 nm or less with respect to the height thereof when the back of the slider is not fixed to the gimbal. The magnetic head chip may be composed of a pair of non-magnetic cores, each of which has a metallic magnetic thin film deposited thereon.

Growing community of inventors

Kumagagaya, Japan

Chiharu Mitsumata