MR Element Research Articles

Effect of Shape on the Bias Field of an Ni-Fe/Ti/Co-Zr-Mo Trilayer MR Element

The effect of shape on the bias field of an Ni-Fe/Ti/Co-Zr-Mo trilayer MR element is discussed in relation to the aim of controlling the bias field of MR heads. In the case of a single-layer Ni-Fe film, the field at half-maximum MR coefficient was found to be proportional to the thickness and the reciprocal of the height. In the case of a trilayer MR element, the saturation bias field was proportional to the Co-Zr-Mo thickness. The bias field was saturated at smaller sense currents, and the saturation bias field increased as the Ti thickness was decreased. The use of a Co-Zr-Mo surface oxidation layer instead of a Ti layer in the trilayer MR element was effective, because it was possible to fabricate the element as a uniform thin film.

Effect of magnetic saturation on reproducing characteristics of magnetoresistive heads

The reproducing characteristics of a magnetoresistive head were studied. Using a two-dimensional finite element method, recording density characteristics and peak shift characteristics of the MR head were estimated with a saturation effect. Recording density characteristics changed with the magnetic saturation of the MR element with a large remanent magnetization and thickness product of the recording medium, but peak shift was not affected by it. Compared with the gap length dependence of the inductive head, the MR head had a lower D/sub 50/ and smaller peak shift than did the inductive head.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Sensitivity distribution asymmetries in magnetoresistive heads with domain control films (abstract)

Suppression of the sidetrack reading behavior is important in achieving⋅high track-density recording with a magnetoresistive head. In the present work, we investigate the sensitivity distribution profiles of MR heads through experimentation using a microtrack technique1 and computer simulation. Shielded, soft, adjacent-layer-biased MR heads with 3∼6−μm-wide tracks are used. The ends of the MR elements are coupled to antiferromagnetic or hard ferromagnetic films for domain control. In the simulation based on the Landau–Lifshitz–Gilbert equation,2 the magnetization configurations in the MR elements of the domain stabilizing films are calculated to analyze the sensitivity distribution. The measured sensitivity profiles in all cases have asymmetries that are reversed when the sensing current direction or the magnetization direction of the MR element is reversed. These results agree with the simulation. The asymmetries of sensitivity profiles are explained by the magnetic poles at the domain control film edges and at the transverse edges of the element which generate a diagonal demagnetizing field distribution in the sensing region.

３層ＭＲ素子Ｎｉ‐Ｆｅ／Ｔｉ／Ｃｏ‐Ｚｒ‐Ｍｏのバイアス磁場に対する形状の影響

The effect of shape on the bias field of an Ni-Fe/Ti/Co-Zr-Mo trilayer MR element is discussed in relation to the aim ofc ontrolling the bias field of an MR head. In the case of an Ni-Fe single film, the field at half-maximum MR coefficient was found to be proportional to the thickness and reclprocal height. In the case of a trilayer MR element, the saturation bias field was found to be proportional to the Co-Zr-Mo thickness. The bias field was saturated at smaller sense currents, and the saturation bias field increased as the Ti thickness decreased. The use of a Co-Zr-Mo surface oxidation layer instead of a Ti film in the trilayer MR element was effective because the element became a uniform and thin film.

MRヘッド再生出力の素子高さ, 膜厚依存性

To take full advantage of the high output of MR head, it is important to optimize the head parameters. Several researchers have calculated the response of an MR element to an external field, but have not devoted sufficient attention to comparing the calculation results and the head characteristics. We investigated an SAL-biased MR head with the design parameters of element height, film thickness, gap length, and flying height, both theoretically and experimentally. The saturation of the head output with the sensing current is well explained by the sensing current density. The average magnetic flux density on the element height increases with a smaller element height. The ratio of the head output to the average magnetic flux density and the sensing current density is almost constant for the element height.

Elements and Devices Based on Magnetorheological Effect*

The magnetorheological suspension (MRS), due to its controllability, can be used as the basis for new devices and technologies. The most important element of any MR device is a magnetorheological transducer (MRT), a controllable hydraulic resistance. Its mathematical model is obtained using quasi-stationary approximation and taking into account the transient processes in the magnetic field inductor. The designs of damping and anti-shock devices using the MR element base are ideologically most simple. A description of such a device is obtained by supplementing the system of equations that describe MRT dynamics with the relations, including hydromechanical pro cesses, in a hydraulic cylinder. MRT can be used to design flexible bridge-like distributors to control hydraulic actuators. The experimental study has shown the possibility of using MRS as a working medium in seals.

Recording Characteristics of MR/Inductive Magnetic Head

Recently the market demand for portable computers has redoubled the need for compact hard disk drives with high storage capacities. The reproduced output from an inductive head depends on the medium velocity, a fact which impedes efforts to obtain higher capacities from small-diameter disk drives. However, the playback output from an MR head does not depend on the medium velocity, making such heads attractive for use in small-diameter drives. In this work, shunt bias in-gap type heads with an MR element in the gap, and SAL (soft adjacent layer) bias piggyback-type heads with an MR element outside the gap, were trial-fabricated, and their recording characteristics were examined. A SAL bias piggyback-type head with read track of width 4.0 μm delivered an output of 300 μV <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">p-p</sub> at 28.6 kFCI, with an error rate of 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-12</sup> .

ＭＲ／インダクティブ磁気ヘッド電磁変換特性

Recently, the demand for making hard disk drive to high capacity and small strengthens by joining to the market of portable computer. Reproduced output depend on medium velocity on inductive head. It is an obstruction to get a large capacity in the small diameter hard disk drive. However, the MR element has domination that large output is obtained in the drive on small diameter hard disk drive which slows of the medium velocity because the reproduced output doesn't depend on the medium velocity. So MR head is paid attention as a magnetic head which achieves making the small diameter hard disk drive to a large capacity. Then, shunt bias In-Gap type with the MR element in the gap and SAL (soft adjacent layer) bias piggyback type with MR element out of gap were made for trial purposes and these two kinds of recording. characteristics were examined in this research. In SAL bias piggyback type of width 4.0μm of the read track, the error rate of 10-12 and 300 μ Vp-p were obtained at 28.6 kFCI.

Recording Characteristics of MR Head for Hard Disk Drive

A disk drive head combining a shunt-biased MR read element and a multi-turn inductive write element, designed for use in 2.5 hard disk drives, was studied in these experiments. The MR element, consisting of an Ni-Fe film, is positioned in the inductive write gap. The write core consists of Mn-Zn ferrite and Co-Zr-Nb-Ta amorphous film, and has a shaped-rail air-bearing surface to achieve high reliability at low flying heights, such as 0.15 ?m. Outputs of 0.54 m p-p in longitudinal recording, and 0.35 m p-p in perpendicular recording, were obtained from the MR-inductive combination head at a medium velocity of 4.7 m/s, a flying height of 0.15 ?m, and a track width of 10.0 ?m. Moreover, in spite of the fact that the MR element did not have a center tap, second harmonic distortions were decreased to less than ?26 dB.

ハードディスク用ＭＲヘッドの電磁変換特性

A disk-drive head combining a shunt biased MR read element and a multi-turn inductive write element is designed for a 2.5″ hard disk drive and was used for these expriments. The MR element, which consists of Ni-Fe film, exists in the inductive write gap. The write core consists of Mn-Zn ferrite and Co-Zr-Nb-Ta amorphous film. It has a Shaped Rail Air Bearing Surface to obtain high reliability at low flying height, such as 0.15μm. Output of 0.54 mVp-p in longitudinal recording and 0.35 mVp-p in perpendicular recording were obtained for the MR-inductive combination head at 4.7 m/s media velocity, 0.15μm flying height and 10.0μm track width. Moreover, in spite of the fact that the MR element did not have center tap, it could decrease second harmonic distortion under -26 dB.

Shielded magnetoresistive head for high density recording

The fabrication process and the head material properties for shielded magnetoresistive heads with planarized lower shields using a tri-layered MR element are described in detail. Applying the etch-back process with low molecular weight polystyrene and CF/sub 4//O/sub 2/ reactive ion etching, the residual step height for a lower shield is dramatically decreased to less than 5% of the initial step height. The tri-layered MR element consists of an MR layer, a magnetic separation layer (MSL), and a soft adjacent layer (SAL). 40-nm thick Ni/sub 81/Fe/sub 19/ (wt.%) films were deposited by evaporation for use as an MR layer. Evaporated Ti MSL thickness was experimentally determined to be 20 nm. Amorphous Co/sub 82/Zr/sub 6/Mo/sub 12/ SAL films exhibited preferable magnetic properties as an SAL material. The fabricated shielded MR heads, using the tri-layered MR element with these NiFe, Ti, and CoZrMo films, provide superior capability to realize high recording density. >

The influence of substrate edge stress on magnetoresistive head anisotropy

It is found that the film anisotropy H/sub k/, in an unshielded magnetoresistive (UMR) sensor is changed after the establishment of a tape-bearing surface. It is demonstrated experimentally and by a theoretical 2-D stress/micromagnetic treatment of the UMR head configuration that the undesirable change in H/sub k/ is caused by the interaction of an anisotropic stress localized in the vicinity of the lapped tape-bearing surface with the UMR element, which inevitably possesses nonzero magnetostriction. The theory predicts that the change in H/sub k/ can be minimized by minimizing the thickness of the SiO/sub 2/ layers used above and beneath the UMR element. by this means and by minimization of MR element magnetostriction, the intrinsic high sensitivity of the UMR sensor can be preserved in a lapped head. >

Inverse effect of magnetostriction in yoke type MR heads

The authors investigated stress induced magnetic anisotropy in yoke type MR heads (YMRH). The distributions of the easy axis in YMRH were calculated from the result of a threo dimonsional stress analysis. When a sputtered NiFe film is used as the upper yoke, if the magnetostriction λs in the MR element is positive and the λs in the upper yoke is negative, the easy axis distribution is such that a stable MR response, can be obtained. We could explain the variations of MR responses as a function of the external stress with our result.

Genetic instability in Drosophila melanogaster: the genetics of an MR element that makes complete P insertion mutations.

An MR element that maps to a specific locus in chromosome 3 of Drosophila melanogaster has the unusual feature of producing complete P (a mobile element) sequence mutations at several X chromosome loci. This MR also increases the frequency of mitotic recombination. Evidence is given for the transposition of MR. The complete P insertion mutations are autonomously unstable and are capable of causing otherwise stable incomplete (defective) P insertion mutations to revert. These results complement the analysis of P element functions with a synthetic complete P derivative. The genetic basis for the mutational-mitotic recombinational components of "hybrid dysgenesis" is conveniently explicable in terms of MR elements present in the genomes of flies present in the wild.

Yoke type MR head on perpendicular double layer media

The configuration of Yoke-type MR Head(YMRH) and reproducing characteristics has been investigated for the memory system, using perpendicular double layer medium, YMRH and thin film writing head. The feature of the YMRH has been clarified by the Finite Element Method(FEM) with vector potential and confirmed experimentally. It has been shown; (i) the thickness of MR element is the most effective to improve the reproducing signal of the YMRH, (ii) the YMRH is suitable for the perpendicular double layer media, (iii) the YMRH has better durability than that of single MR Head(MRH). We realized the digital memory system of high bit transfer rate of 85MBPS. It is concluded that the combination of YMRH and perpendicular double layer media is useful for the high density magnetic recording.

Magnetic head and method of production thereof

A magnetic head and a production method therefore in which permanent magnet films for applying a DC bias magnetic field Hd h to a magnetoresistive effect element film (MR element film) is arranged on both sides of the thickness dimension of the MR element film through at least a non-magnetic film therebetween. In making the MR element film thicker in order to reduce distortion, the DC bias magnetic field Hd b to be applied to the MR element film is also required to be increased. Unlike the prior art in which the above-mentioned requirement is met by increasing the thickness of the permanent magnet film under the thickness of the MR element film resulting in the problem of breakage of a film member above or under the thickness of the permanent magnet film, the invention further comprises a second permanent magnet film above the thickness of the MR element film without increasing the thickness of the first permanent magnet film. In the case of a magnetic head with a shield members of soft magnetic material holding the MR element film from both sides of the thickness thereof, the MR element film is made thicker to make reproduction possible without any distortion or without substantially increasing the gap. For this purpose, the MR element film is held on the sides above and under the thickness thereof by first and second permanent magnet films which in turn are held by the shield members. To minimize distribution of the MR element film, a comparatively high-temperature process after forming of the MR element film i.e., forming of the second permanent magnet film is effected at optimum temperature, and a magnetic field is applied along the magnetic easy axis of the MR element film.

Measurement of stripe head velocity using magneto-resistance signal

Stripe head velocity has been measured by monitoring the signal from a straight magneto-resistive element as a stripe expands and contracts along the element. The MR element provides a path for the stripe as well as indicating its position versus time. This new measurement technique allows continuous monitoring of the stripe velocity as drive and in-plane field are varied. An ion-implanted garnet film of composition Y1.95Sm0.09Lu0.09Ca0.87Ge0.87Fe4.13O 12 with a thickness of 2.0 μm was measured using an MR element 0.04 μm thick, 4 μm wide, and 150 μm in length. The in-plane field H1 is approximately perpendicular to the stripe head velocity. Two types of velocity behavior are observed depending on the direction of H1×V. For H1×V pointing toward the implanted surface, the velocity versus drive depends on the H1 magnitude. For H1&amp;lt;50 Oe, the velocity versus drive is linear up to a velocity instability above which the velocity tends to saturate. The instability is assigned as a horizontal Bloch line motion. For H1≳100 Oe, the velocity increases to a much higher value which is in agreement with the terminal velocity formula, (π/2) γΔH1. For 50&amp;lt;H1&amp;lt;100 Oe, the velocity curve shows the horizontal Bloch line instability; but at higher drive the velocity suddenly increases up to the terminal velocity. For H1×V pointing toward the nonimplanted surface, the velocity curve has a weak instability at low drive followed by a concave shape.