Tdk Corporation

Sae Magnectics (h.k.) Ltd.

Takumi Uesugi

Takeo Kagami

Satoshi Miura

Tetsuro Sasaki

Yoshihiro Tsuchiya

Kei Hirata

Satoru Araki

Norio Takahashi

Masashi Sano

Shunji Saruki

Kosuke Tanaka

Kazuki Sato

Koichi Terunuma

Tsuyoshi Umehara

Yosuke Antoku

Masaru Hirose

Chi Man Lee

Kwok Piu Tso

A magnetic field detecting element has a first lower layer, a second lower layer, a tunnel barrier layer, and an upper layer, wherein the first lower layer, the second lower layer, the tunnel barrier layer, and the upper layer are stacked adjacent to each other in this order, the first lower layer is formed in an amorphous state; and the second lower layer is made of cobalt, iron, nickel or a combination thereof and that is formed in a substantially amorphous state, the second lower layer being in touch with the first lower layer and the tunnel barrier layer on both sides and a film thickness of the second lower layer is approximately between 0.2 and 1.5 nm.

Magnetic field detecting element having a tunnel barrier formed on an amorphous layer

A noise-testing method for a thin-film magnetic head with an MR read head element and a heating unit capable of applying a heat and a stress to the MR read head element, includes a step of applying alternately and discontinuously with each other an electrical power having a first level and an electrical power having a second level higher than the first level to the heating unit, and a step of evaluating the thin-film magnetic head by measuring a noise output or noise outputs obtained from the MR read head element when the electrical power or the electrical powers are applied to the heating unit.

Method for testing noise of thin-film magnetic head, and magnetic disk drive apparatus with noise testing function

An MR element incorporates a layered structure. The layered structure includes: a spacer layer having a first surface and a second surface that face toward opposite directions; a free layer disposed adjacent to the first surface of the spacer layer and having a direction of magnetization that changes in response to a signal magnetic field; and a pinned layer disposed adjacent to the second surface of the spacer layer and having a fixed direction of magnetization. The spacer layer is a layer at least part of which is made of a material other than a conductor, and the spacer layer intercepts the passage of currents or limits the passage of currents as compared with a layer entirely made of a conductor. The MR element further incorporates a conductive film that is disposed on the peripheral surface of the layered structure and allows conduction between the free layer and the pinned layer.

Magnetoresistive element incorporating conductive film disposed on peripheral surface of layered structure including spacer layer, free layer and pinned layer, the conductive film allowing conduction between the free layer and the pinned layer

Provided is a thin-film magnetic head in which a noise due to the voltage potential difference between the read head element and the protective coat surface is suppressed. The thin-film magnetic head comprises: a read head element, one end surface of the read head element reaching an head end surface on the ABS side; a protective coat formed on the head end surface in such a way to cover at least the one end surface of the read head element; and at least one antistatic means for preventing the protective coat from being electrostatically charged, formed on/above the element formation surface, one end surface of the at least one antistatic means reaching the head end surface, the protective coat covering a portion, not the whole, of the one end surface of the at least one antistatic means on the head end surface.

Thin-film magnetic head having an antistatic layer preventing a protective coat from being electrostatically charged

An exchange-coupling film incorporates an antiferromagnetic layer and a pinned layer. The pinned layer includes a first ferromagnetic layer, a second ferromagnetic layer, a third ferromagnetic layer, a nonmagnetic middle layer, and a fourth ferromagnetic layer that are disposed in this order, the first ferromagnetic layer being closest to the antiferromagnetic layer. The first ferromagnetic layer is made of a ferromagnetic material and has a face-centered cubic structure. The second ferromagnetic layer is made of only iron or an alloy containing x atomic % cobalt and (100&#x2212;x) atomic % iron, wherein x is greater than zero and smaller than or equal to 60. The third ferromagnetic layer is made of an alloy containing y atomic % cobalt and (100&#x2212;y) atomic % iron, wherein y is within a range of 65 to 80 inclusive. The antiferromagnetic layer and the first ferromagnetic layer are exchange-coupled to each other. The third and fourth ferromagnetic layers are antiferromagnetically coupled to each other.

Exchange-coupling film incorporating stacked antiferromagnetic layer and pinned layer, and magnetoresistive element including the exchange-coupling film

A magneto-resistive element has a lower layer, a tunnel barrier layer, and an upper layer. The lower layer, the tunnel barrier layer, and the upper layer are disposed adjacent to each other and are stacked in this order. A magnetization direction of either of the lower layer and the upper layer is fixed relative to an external magnetic field, and a magnetization direction of the other layer is variable in accordance with the external magnetic field. A crystalline portion and a non-crystalline portion co-exist in a plane that is parallel with a surface of the tunnel barrier layer.

TMR element having a tunnel barrier which includes crystalline portions and non-crystalline portions

A testing method of a thin-film magnetic head has an MR read head element with a multi-layered structure including a magnetization-fixed layer, a magnetization-free layer and a nonmagnetic intermediate layer or a tunnel barrier layer sandwiched between the magnetization-fixed layer and the magnetization-free layer. The method includes a step of feeding through the MR read head element a sense current, a step of measuring non-signal output versus frequency characteristics of the MR read head element over a frequency range that covers at least FMR of the magnetization-fixed layer, and a step of discriminating whether the thin-film magnetic head is a head providing high-temperature noises by comparing a frequency of a peak of the non-signal output resulting from FMR of the magnetization-fixed layer with a threshold.

Testing method and apparatus of thin-film magnetic head

An MR element comprises: a tunnel barrier layer having two surfaces that face toward opposite directions; a free layer disposed adjacent to one of the surfaces of the tunnel barrier layer and having a direction of magnetization that changes in response to an external magnetic field; and a pinned layer that is a ferromagnetic layer disposed adjacent to the other of the surfaces of the tunnel barrier layer and having a fixed direction of magnetization. The free layer incorporates: a first soft magnetic layer disposed adjacent to the one of the surfaces of the tunnel barrier layer; a high polarization layer disposed such that the first soft magnetic layer is sandwiched between the tunnel barrier layer and the high polarization layer; and a second soft magnetic layer disposed such that the high polarization layer is sandwiched between the first and second soft magnetic layers.

Magnetoresistive element, thin-film magnetic head, head gimbal assembly, head arm assembly and magnetic disk drive

A magneto-resistive device is provided for contributing to a higher MR ratio and a reduced cleaning time for cleaning the surface of a cap layer. In the magneto-resistive device, a cap layer which serves as a protection layer is formed on a free layer which is the topmost layer of a magneto-resistive layer constituting a TMR devise. An upper electrode which is additionally used as an upper magnetic shield is electrically connected to the free layer through an upper metal layer. The cap layer comprised of a two-layer film made up of a conductive layer closer to the free layer and a topmost conductive layer. The conductive layer closer to the free layer is made of a material having higher oxygen bond energy than Ru, such as Zr, Hf, or the like. The topmost conductive layer is made of a material having lower oxygen bond energy, such as a noble metal or the like.

Magneto-resistive device, and magnetic head, head suspension assembly and magnetic disk apparatus using magneto-resistive device

A magnetic storage cell including of two magneto-resistive elements to remove in-phase noise in a read output, and reduces a loss of a current magnetic field, when information is written thereinto, to efficiently produce magnetization reversal. In addition, the area occupied by the magnetic storage cell is reduced to increase the storage capacity, and the structure of the magnetic storage cell is simplified to facilitate the manufacturing. The magnetic storage cell including two TMR elements, and an annular magnetic layer provided commonly for the two TMR elements. The TMR elements are disposed in a direction along a laminating surface with respect to each other. A write bit line and a write word line are provided commonly for the two TMR elements. The annular magnetic layer is disposed with its axial direction defined in a direction along the laminating surface, and is passed through by the lines.

Magnetic storage cell and magnetic memory device using same

An upper metal layer made of a non-magnetic metal is formed as a protection layer on the top surface of a free layer positioned topmost of a magneto-resistive layer constituting a TMR device. An upper electrode, serving additionally as an upper magnetic shield layer, is electrically connected to the free layer through an underlying layer of the upper electrode, and the upper metal layer. The thickness of the upper metal layer is chosen to be 10 nm or more.

Magneto-resistive device, and magnetic head and head suspension assembly using same

Provided are a magnetic transducer having good thermal stability, a thin film magnetic head, a method of manufacturing a magnetic transducer and a method of manufacturing a thin film magnetic head. A stack of an MR element has a stacked structure comprising an underlayer, a first soft magnetic layer, a second soft magnetic layer, a nonmagnetic layer, a ferromagnetic layer, an antiferromagnetic layer and a capping layer, which are stacked in this order on the underlayer. The ferromagnetic layer is divided into a bottom layer and a top layer in the direction of stack. A ferromagnetic interlayer having magnetism and having higher electrical resistance than the electrical resistance of the ferromagnetic layer is formed between the bottom layer and the top layer. The ferromagnetic interlayer magnetically integrates the bottom layer with the top layer and limits a path for electrons moving through the stack, thereby improving the rate of resistance change. Furthermore, the ferromagnetic interlayer contains, as an additive, at least one element in a group consisting of Mn, Cr, Ni, Cu, Rh, Ir and Pt and thus prevents heat deterioration in the stack.

Magnetic transducer, thin film magnetic head, method of manufacturing magnetic transducer and method of manufacturing thin film magnetic head

A magneto-resistive device has a magneto-resistive layer laminated between electrodes. The magneto-resistive layer has a non-magnetic layer, a pinned layer and a free layer sandwiching the non-magnetic layer, and a pin layer formed on the pinned layer on the opposite side to the free layer. The pin layer is formed in a region which substantially overlaps with an effective region in a film plane direction in which a current flows in a direction substantially perpendicular to the film plane between the electrodes in a predetermined thickness, and is formed in a region which does not substantially overlap with the effective region substantially in the same thickness as the predetermined thickness or in a thickness smaller than the predetermined thickness, continuous from the region which substantially overlaps with the effective region.

Provided are a magnetic transducer having a higher rate of resistance change and a larger magnitude of resistance change and having better stability of properties, and a thin film magnetic head. A stack of an MR element has a stacked structure comprising an underlayer, an antiferromagnetic layer, a ferromagnetic layer, a first nonmagnetic layer, a first soft magnetic layer, a second soft magnetic layer, a second nonmagnetic layer and a high-resistance layer, which are stacked in sequence on the underlayer. The orientation of magnetization of the ferromagnetic layer is fixed by exchange coupling between the ferromagnetic layer and the antiferromagnetic layer. The orientations of magnetizations of the first soft magnetic layer and the second soft magnetic layer change according to an external magnetic field. Electrical resistance of the stack changes according to a relative angle between the orientations of the magnetizations of the first soft magnetic layer and the second soft magnetic layer and the orientation of the magnetization of the ferromagnetic layer. The high-resistance layer has higher electrical resistance than electrical resistance of the second nonmagnetic layer. The second nonmagnetic layer and the high-resistance layer are provided on the side of the second soft magnetic layer opposite to the first nonmagnetic layer. Thus, the rate of resistance change and the magnitude of resistance change can be increased, and furthermore stability of properties can be improved.

Magnetic transducer with a higher rate and larger magnitude of resistance change

Provided are a magnetic transducer and a thin film magnetic head having good thermal stability and capable of obtaining a high exchange coupling magnetic field, a method of manufacturing a magnetic transducer and a method of a manufacturing a thin film magnetic head. An MR element has a stack having a stacked structure comprising an underlayer, a crystal-growth inhibitor layer, a first soft magnetic layer, a second soft magnetic layer, a nonmagnetic layer, a ferromagnetic layer, an antiferromagnetic layer and a cap layer, which are stacked in sequence. The ferromagnetic layer has an inner ferromagnetic layer, a coupling layer and an outer ferromagnetic layer, which are stacked in this order on the nonmagnetic layer. The crystal-growth inhibitor layer inhibits crystal growth of the layers formed on the crystal-growth inhibitor layer, thereby limiting an average in-surface particle diameter of the inner ferromagnetic layer to within the range of from 3 nm to 8 nm inclusive, so that an interface between the coupling layer and the inner ferromagnetic layer becomes flattened.

Growing community of inventors

Tokyo, Japan

Takumi Uesugi