A nonvolatile magnetic random access memory (MRAM) is an array of individual magnetic memory cells. Each memory cell is a magnetic tunnel junction (MTJ) element and a diode electrically connected in series. Each MTJ is formed of a pinned ferromagnetic layer whose magnetization direction is prevented from rotating, a free ferromagnetic layer whose magnetization direction is free to rotate between states of parallel and antiparallel to the fixed magnetization of the pinned ferromagnetic layer, and an insulating tunnel barrier between and in contact with the two ferromagnetic layers. Each memory cell has a high resistance that is achieved in a very small surface area by controlling the thickness, and thus the electrical barrier height, of the tunnel barrier layer. The memory cells in the array are controlled by only two lines, and the write currents to change the magnetic state of an MTJ, by use of the write currents' inherent magnetic fields to rotate the magnetization of the free layer, do not pass through the tunnel barrier layer. All MTJ elements, diodes, and contacts are vertically arranged at the intersection regions of the two lines and between the two lines to minimize the total MRAM surface area. The power expended to read or sense the memory cell's magnetic state is reduced by the high resistance of the MTJ and by directing the sensing current through a single memory cell.

Magnetic memory array using magnetic tunnel junction devices in the memory cells

There are provided a magnetoresistance effect element, a magnetic head, a magnetic head assembly and a magnetic recording system, which have high sensitivity and high reliability. The magnetoresistance effect element has two ferromagnetic layers, a non-magnetic layer provided between the ferromagnetic layers, and a layer containing an oxide or nitride as a principal component, wherein the layer containing the oxide or nitride as the principal component contains a magnetic transition metal element which does not bond to oxygen and nitrogen and which is at least one of Co, Fe and Ni.

Magnetoresistance effect element

A magnetic tunnel junction (MTJ) device is usable as a magnetic field sensor or as a memory cell in a magnetic random access (MRAM) array. The MTJ device has a "pinned" ferromagnetic layer whose magnetization is oriented in the plane of the layer but is fixed so as to not be able to rotate in the presence of an applied magnetic field in the range of interest, a "free" ferromagnetic layer whose magnetization is able to be rotated in the plane of the layer relative to the fixed magnetization of the pinned ferromagnetic layer, and an insulating tunnel barrier layer located between and in contact with both ferromagnetic layers. The pinned ferromagnetic layer is pinned by interfacial exchange coupling with an adjacent antiferromagnetic layer. The amount of tunneling current that flows perpendicularly through the two ferromagnetic layers and the intermediate tunnel barrier layer depends on the relative magnetization directions of the two ferromagnetic layers. The ferromagnetic layers are formed in two separate spaced-apart planes that do not overlap in the region of the tunnel barrier layer, thereby eliminating any extraneous magnetic poles.

Magnetic tunnel junctions with controlled magnetic response

A new hybrid magnetic spin injected-FET structure can be used as a memory element for the nonvolatile storage of digital information, as well as in other environments, including for example logic applications for performing digital combinational tasks, or a magnetic field sensor. The hybrid FET uses ferromagnetic materials for the source and drain, and like a conventional FET, has two operating states determined by a gate voltage, "off" and "on". The ferromagnetic layers of the hybrid FET are fabricated to permit the device to have two stable magnetization states, parallel and antiparallel. In the "on" state the spin injected FET has two settable, stable resistance states determined by the relative orientation of the magnetizations of the ferromagnetic source and drain. An external magnetic field can change the magnetization state of the device by orienting the magnetization of the drain to be parallel or antiparallel with that of the source, thus changing the resistance of the device to a current of spin polarized electrons injected into the source and flowing to the drain through the channel under the gate. The new FET can be used as a memory cell because the drain magnetization is non-volatile, and can represent a binary data value to be stored in the cell. A conductive write line can be used for inductively coupling an input magnetic field (representing a data value to be stored in the device) with the drain magnetization to alter the orientation state of the latter. An array of spin injected FETs can be coupled together in an array to form a new hybrid FET memory array. The new FET can also be used as a logic gate that stores the result of a boolean function. A magnetic field generated by the combined current of one or more input data signals is coupled to the spin injected FET. Depending on the particular function to be implemented, the ferromagnetic drain magnetization can be configured to change or retain its orientation based on particular predefined combinations of input data signals.

Magnetic spin injected field effect transistor and method of operation

There is provided a practical magnetoresistance effect element which has an appropriate value of resistance, which can be sensitized and which has a small number of magnetic layers to be controlled, and a magnetic head and magnetic recording and/or reproducing system using the same. In a magnetoresistance effect element wherein a sense current is caused to flow in a direction perpendicular to the plane of the film, a resistance regulating layer is provided in at least one of a pinned layer, a free layer and an non-magnetic intermediate layer. The resistance regulating layer contains, as a principal component, an oxide, a nitride, a fluoride, a carbide or a boride. The resistance regulating layer may be a continuous film or may have pin holes. Thus, it is possible to provide a practical magnetoresistance effect element which has an appropriate value of resistance, which can be sensitized and which has a small number of magnetic layers, while effectively utilizing the scattering effect depending on spin.

Magnetoresistance effect element, magnetic head and magnetic recording and/or reproducing system

An on-off device disposed at each of the inlet and the outlet of a fluid controller is one of five kinds of on-off devices, i.e., on-off device having a two-port valve, on-off device having a two-port valve and a three-port valve, on-off device having a two-port valve and two three-port valves, on-off device having two three-port valves, and on-off device having three three-port valves, The main bodies of two-port valves of all types of on-off devices are identical in configuration and each have an inlet and an outlet in a bottom face thereof. Main bodies of three-port valves of all types of on-off devices are identical in configuration and each formed in a bottom face thereof with an inlet, an outlet always in communication with the inlet, and an inlet-outlet subopening.

Fluid control apparatus

A MR element which has a basically three-layered structure wherein the first and the second magnetic layer sandwich the nonmagnetic layer or of a basically five-layered structure wherein nonmagnetic layers are sandwiched between the first and second magnetic layers and between the second and third magnetic layers, respectively. The MR element of such arrangement offers a surprisingly large MR ratio under application of a sufficiently low magnetic field despite such a simple arrangement thereof.

Magnetoresistive element and devices utilizing the same

A method for magnetically recording/reproducing comprising recording an information signal by forming a pattern of a soft magnetic material in a magnetic recording medium; providing a magnetoeletric converting element in a place neighboring a face of forming the pattern of the magnetic recording medium on which the pattern is formed, applying a magnetic field to the pattern; and reproducing the information by detecting a variation of the magnetic field caused by the pattern of the soft magnetic material of the magnetic recording medium while relatively moving the magnetoelectric converting element and the magnetic recording medium.

Magnetic recording medium

A magnetic thin film memory is provided including a plurality of magnetic thin film memory elements each adapted to record information on the basis of the direction of magnetization of a magnetic thin film thereof, the magnetic thin film memory elements being each composed of at least the magnetic thin film and a switching element. With such a constitution the magnetic thin film memory can be reduced in size while a sufficiently large signal can be obtained with a substantially improved SN ratio. A method for recording and reproduction information using the magnetic thin film memory is also provided. In another aspect, the present invention provides a magnetic thin film memory element including at least two kinds of magnetic layer, and a nonmagnetic layer which is interposed between the magnetic layers wherein the two kinds of magnetic layers are stacked so as to be coupled to each other by an exchange interaction through the nonmagnetic layer.

Magnetic thin film memory and recording/reproduction method therefor

A magnetic thin film memory wherein the memory is composed of magnetic thin films with a layer of a higher coercive force and a layer of a lower coercive force via a nonmagnetic layer laminated repetitively, or magnetic thin films having the easy magnetization axis which lies between the perpendicular and the horizontal directions of the magnetic thin film, and information is recorded on the layer of a lower coercive force, or information is recorded by changing the direction of the magnetization by means of a magnetic field applied by two recording lines which cross the magnetic thin film, thereby to obtain a sufficient amplitude of reproduction signal even when the size of the memory is reduced.

Yuji Kawano

Papers

Fluid control apparatus

Magnetoresistive element and devices utilizing the same

Magnetic recording medium

Magnetic thin film memory and recording/reproduction method therefor

Magnetic thin film memory