142 results about "Perpendicular magnetization" patented technology

A method and system for providing a magnetic element that can be used in a magnetic memory is disclosed. The method and system include providing a first pinned layer, a barrier layer, a free layer, a conductive nonmagnetic spacer layer, and a second pinned layer. Each pinned layer has a pinned layer easy axis. At least a portion of the pinned layer easy axis is in a perpendicular direction. The barrier layer resides between the first pinned layer and the free layer. The spacer layer is between the free layer and the second pinned layer. The free layer has a free layer easy axis, at least a portion of which is in the perpendicular direction. The magnetic element is also configured to allow the free layer to be switched due to spin transfer effect when a write current is passed through the magnetic element. Because of the perpendicular magnetization(s), the writing current for spin transfer may be significantly reduced.

It is intended to reduce the media noise, and to improve the recording density dependence of read output voltage. The present invention provides a perpendicular magnetic recording media and its manufacturing process, wherein a perpendicular magnetic recording medium comprises a soft magnetic underlayer film and a perpendicular magnetizing film, these films being formed on a substrate in this order, a smoothness control film such as Cr film, being inserted between the substrate and the soft magnetic underlayer film. Therefore, perpendicular orientation and surface smoothness are improved for the perpendicular magnetizing film laminated on the smooth surface of the soft magnetic underlayer film. As the perpendicular orientation is improved for the perpendicular magnetizing film, the initial layer is reduced, thereby media noise being lowered and recording density dependence of read output voltage being improved. In addition, as the surface smoothness is improved for the perpendicular magnetizing film, sliding characteristics of a recording/reproducing head is also improved, thereby this also lowering the media noise.

A magnetic thin film element is provided with a magnetoresistive film including a first magnetic layer composed of a perpendicular magnetization film, a second magnetic layer composed of a perpendicular magnetization film having a higher coercive force than that of the first magnetic layer, and a nonmagnetic layer interposed between the first magnetic layer and the second magnetic layer. The resistance of the magnetoresistive film varies depending on whether or not the magnetic spins of the first magnetic layer and the second magnetic layer are in the same direction.

A magnetic memory element capable of maintaining high thermal stability (retention characteristics) while reducing a writing current. The magnetic memory element includes a magnetic tunnel junction having a first magnetic body including a perpendicular magnetization film, an insulating layer, and a second magnetic body serving as a storage layer including a perpendicular magnetization film, which are sequentially stacked. A thermal expansion layer is disposed in contact with the magnetic tunnel junction portion. The second magnetic body is deformed in a direction in which the cross section thereof increases or decreases by the thermal expansion or contraction of the thermal expansion layer due to the flow of a current, thereby reducing a switching current threshold value required to change the magnetization direction.

A magnetic memory element and a method of driving such an element are disclosed. The magnetic memory element has a magnetic tunnel junction portion with a spin-valve structure having a perpendicular magnetization free layer formed of a perpendicular magnetization film, a perpendicular magnetization pinned layer formed of a perpendicular magnetization film, and a nonmagnetic layer sandwiched between the perpendicular magnetization free layer and the perpendicular magnetization pinned layer, and records information by application of an electric pulse to the magnetic tunnel junction portion. An in-plane magnetization film, interposed in the path of the electric pulse, is disposed in the magnetic tunnel junction portion. The in-plane magnetization film is configured so as to exhibit antiferromagnetic (low-temperature)-ferromagnetic (high-temperature) phase transitions depending on temperature changes based on application of the electric pulse to the magnetic tunnel junction portion.

A multi-bit cell of magnetic random access memory comprises a magnetic tunnel junction element including a first and second free layer comprising a changeable magnetization oriented substantially perpendicular to a layer plane in its equilibrium state and a switching current, a first and second tunnel barrier layer, and a pinned layer comprising a fixed magnetization oriented substantially perpendicular to a layer plane, the pinned layer is disposed between the first and second free layers and is separated from the free layers by one of the tunnel barrier layers, a selection transistor electrically connected to a word line, and a bit line intersecting the word line. The magnetic tunnel junction element is disposed between the bit line and the selection transistor and is electrically connected to the bit line and the selection transistor, wherein the first and second free layers have substantially different switching currents.

In a magnetoresistive element of a magnetic memory, a inversion field Hc of at least a first magnetic layer is given by $\mathrm{Hc}=\frac{2\left(\mathrm{Ku}-2\pi {\mathrm{Ms}}^{2}f\right)}{\mathrm{Ms}}$

where Ku and Ms are the perpendicular magnetic anisotropy constant and saturation magnetization of the first magnetic layer. The inversion field Hc is set smaller than a magnetic field generated by a magnetic field generation mechanism. Letting T be the film thickness of the first magnetic layer and W be the width and length, f is a factor given by

f=7×10⁻¹³(T/W)⁴−2×10⁻⁹(T/W)³+3×10⁻⁶(T/W)²−0.0019(T/W)+0.9681

A magnetic memory manufacturing method is also disclosed.

A multi-bit cell of magnetic random access memory comprises a magnetoresistive element including first and second free layers, each free layer comprising a reversible magnetization direction directed substantially perpendicular to a layer plane in its equilibrium state and a switching current, first and second tunnel barrier layers, and a pinned layer comprising a fixed magnetization direction directed substantially perpendicular to the layer plane, the pinned layer is disposed between the first and second free layers and is separated from the free layers by one of the tunnel barrier layers; a selection transistor electrically connected to a word line, and a bit line intersecting the word line; the magnetoresistive element is disposed between the bit line and the selection transistor and is electrically connected to the bit line and the selection transistor, wherein the first and second free layers have substantially different switching currents.

A magnetooptical recording medium includes a first magnetic layer, a second magnetic layer whose Curie temperature is lower than that of the first magnetic layer, and a third magnetic layer, comprising a vertically-magnetizing film, whose Curie temperature is higher than that of the second magnetic layer. The first magnetic layer, the second magnetic layer and the third magnetic layer are in a state of exchange coupling with each other at a portion of a vertically-magnetizing film. A domain walls formed in the first magnetic layer moves when the temperature of the medium has been raised to at least the Curie temperature of the second magnetic layer.

Embodiments of the present invention provide a perpendicular magnetic recording medium suitable for high density recording. According to one embodiment, a magnetic recording layer comprises four layers in which a first magnetic layer, a magnetic coupling layer, a second magnetic layer, and a third magnetic layer are formed above a substrate. The first magnetic layer and the second magnetic layer are perpendicular magnetization films containing an oxide, and ferromagnetically coupled with each other by way of the magnetic coupling layer, and they are, more preferably, a Co alloy layer containing an oxide. The third magnetic layer is ferromagnetically coupled with the second magnetic layer. The concentration of the oxide contained in the third magnetic layer is lower than the concentration of the oxide in the second recording layer, or the third magnetic layer does not contain the oxide. In this case, magnetic property is set for the anisotropic magnetic field Hk1 of the first magnetic layer and the anisotropic magnetic field Hk2 of the second magnetic layer, so as to satisfy: Hk1>Hk2.

A method for measuring the frequency in a spin torque oscillator having at least a magnetic oscillation layer (MOL), junction layer, and magnetic reference layer (MRL) is disclosed. In a first embodiment, a small in-plane magnetic field is applied to the STO after a DC current is applied to excite the MOL into an oscillation state. The MRL has a perpendicular magnetization that is tilted slightly to give an in-plane magnetization component to serve as a reference layer for measuring the oscillation frequency of the MOL in-plane magnetization component. An AC voltage change is produced in the DC current as a result of variable STO resistance and directly correlates to MOL oscillation frequency. Alternatively, a field having both perpendicular and in-plane components may be applied externally or by forming the STO between two magnetic poles thereby producing an in-plane magnetization reference component in the MRL.

A perpendicular STT-MRAM comprises apparatus, a method of operating and a method of manufacturing a spin-torque magnetoresistive memory and a plurality of magnetoresistive memory element having a recording layer which has an interface interaction with an underneath dielectric functional layer. The energy switch barrier of the recording layer is reduced under an electric field applying along a perpendicular direction of the functional with a proper voltage on a digital line from a control circuitry; accordingly, the perpendicular magnetization of the recording layer is readily reversible in a low spin-transfer switching current.

A spin transistor useful for device miniaturization and high-density integration is provided. The spin transistor includes: a semiconductor substrate including a channel layer; ferromagnetic source and drain disposed on the semiconductor substrate to be separated from each other and to be magnetized in a direction perpendicular to a surface of the channel layer; a gate formed on the semiconductor substrate between the source and the drain to adjust spins of electrons passing through the channel layer, wherein spin-polarized electrons are injected from the source to the channel layer, and the electrons injected into the channel layer pass though the channel layer and are injected into the drain, and wherein the spins of the electrons passing through the channel layer undergo precession due to a spin-orbit coupling induced magnetic field according to a voltage of the gate.

A device or class of devices that provides a mechanism for controlling charge current flow in transistors that employs collective magnetic effects to overcome voltage limitations associated with single-particle thermionic emission as in conventional MOSFETs. Such a device may include two or more magnetic stacks with an easy-in-plane ferromagnetic film sandwiched between oppositely magnetically oriented perpendicular magnetization anisotropy (PMA) ferromagnets. Each stack includes two non-magnetic layers separating the easy-plane ferromagnetic film from the PMA layers. Charge current flow through one of these stacks controls the current-voltage negative differential resistance characteristics of the second stack through collective magnetic interactions. This can be exploited in a variety of digital logic gates consuming less energy than conventional CMOS integrated circuits. Furthermore, the easy-in-plane magnetic films may be subdivided into regions coupled through exchange interactions and the in-plane fixed magnetic layers in the input magnetic stacks can be used in non-volatile logic and memory.

A magnetoresistive film includes a nonmagnetic film, and a structure in which magnetic films are formed on the two sides of the nonmagnetic film. At least one of the magnetic films is a perpendicular magnetization film. A magnetic film whose easy axis of magnetization is inclined from a direction perpendicular to the film surface is formed at a position where the magnetic film contacts the perpendicular magnetization film but does not contact the nonmagnetic film. A memory, magnetic element, magnetoresistive element, and magnetic element manufacturing method are also disclosed.

A thin film magnet and a cylindrical ferromagnetic thin film having a high maximum energy product (greater than 120 kJ/m3) and thus suitable for use in miniature high performance devices are provided. The thin film magnet is produced by means of physical vapor deposition. The thin film magnet is an (Nd1-xRx)yM1-y-zBz alloy having a ferromagnetic compound of the Nd2Fe14B type as its main phase, wherein R is Tb, Ho, and Dy and M is Fe metal or an Fe-based alloy including at least one of Co and Ni, 0.04</=x</=0.10,0.11</=y</=0.15, and 0.08</=z</=0.15. A perpendicular magnetization film having such a composition is deposited on the side wall of a substrate in the columnar (or cylindrical) form thereby obtaining a cylindrical ferromagnetic thin film having radial anisotropy.

Provided is a structure having a perpendicular magnetization film which is an (Mn_1-x,Ga_x)₄N_1-y (0<x≦0.5, 0<y<1) thin film having a nitrogen-deficient composition which is formed by controlling and introducing nitrogen N into an MnGa alloy or a thin film containing at least one of Ge, Zn, Sb, Ni, Ag, Sn, Pt, and Rh, instead of Ga. The perpendicular magnetization film exhibits a Curie temperature sufficiently higher than room temperature, has saturation magnetization smaller than that of existing materials, and is capable of being fabricated as a very flat film.