306 results about "Antiferromagnetic coupling" patented technology

A method and system for providing a magnetic element capable of being written using spin-transfer effect while being thermally stable and a magnetic memory using the magnetic element are disclosed. The magnetic element includes a first, second and third pinned layers, first and second nonmagnetic layers, a free layer and a nonmagnetic spacer layers. The first, second and third pinned layers are ferromagnetic and have first, second and third magnetizations pinned in first, second and third directions. The first and second nonmagnetic layers include first and second diffusion barriers, respectively. The first and second nonmagnetic layers are between the first and second pinned layers and the second and third pinned layers, respectively. The first and second pinned layers and the second and third pinned layers are antiferromagnetically coupled. The nonmagnetic spacer layer is conductive and resides between the free layer and the third pinned layer. In addition, performance can be further improved by doping Co containing ferromagnetic layers with Cr and/or Pt.

A magnetic recording head includes a recording magnetic pole, and a spin oscillation device including a first magnetic layer having at least one magnetic material layer, a second magnetic layer having at least one magnetic material layer, and a first nonmagnetic layer provided between the first magnetic layer and the second magnetic layer. The first magnetic layer and the second magnetic layer are antiferromagnetically coupled and/or magnetostatically coupled to each other. The first magnetic layer and the second magnetic layer are laminated in a direction generally parallel to a medium facing surface and generally parallel to a side surface of the recording magnetic pole intersecting with the medium facing surface.

Magnetic tunnel junction (“MTJ”) element structures and methods for fabricating MTJ element structures are provided. An MTJ element structure may comprise a crystalline pinned layer, an amorphous fixed layer, and a coupling layer disposed between the crystalline pinned layer and the amorphous fixed layer. The amorphous fixed layer is antiferromagnetically coupled to the crystalline pinned layer. The MTJ element further comprises a free layer and a tunnel barrier layer disposed between the amorphous fixed layer and the free layer. Another MTJ element structure may comprise a pinned layer, a fixed layer and a non-magnetic coupling layer disposed therebetween. A tunnel barrier layer is disposed between the fixed layer and a free layer. An interface layer is disposed adjacent the tunnel barrier layer and a layer of amorphous material. The first interface layer comprises a material having a spin polarization that is higher than that of the amorphous material.

A magnetic recording medium includes a substrate, an underlayer, a lower magnetic layer formed on the underlayer, an intermediate layer, and an upper magnetic layer formed on the intermediate layer. The intermediate layer is typically Ru, and promotes antiferromagnetic coupling between the upper and lower magnetic layers. The upper and lower magnetic layers are typically Co alloys. The lower magnetic layer has a high saturation magnetization Ms to promote high exchange coupling between the upper and lower magnetic layers. The dynamic coercivity of the lower magnetic layer is lower than the exchange field to ensure rapid switching of the lower magnetic layer.

A magnetic memory cell including a soft magnetic layer and a coupling layer, and methods of operating the memory cell are provided. The memory cell includes a stack with a free ferromagnetic layer and a pinned ferromagnetic layer, and a soft magnetic layer and a coupling layer may also be formed as layers in the stack. The coupling layer may cause antiferromagnetic coupling to induce the free ferromagnetic layer to be magnetized in a direction antiparallel to the magnetization of the soft magnetic layer, or the coupling layer may cause ferromagnetic coupling to induce the free ferromagnetic layer to be magnetized in a direction parallel to the magnetization of the soft magnetic layer. The coupling layer, through a coupling effect, reduces the critical switching current of the memory cell.

A basic design is disclosed for bottom shield (S1) and top shield (S2) of the reader shields in a magnetic read-write head. The critical part of new design includes an antiferromagnetic film which pins an antiferromagnetically coupled trilayer (AFCT). The simplest embodiment for top shield, for example, would be a film sequence of FM/Ru/FM/AFM. This replaces the normal top shield design which typically comprises a ferromagnetic seed layer and a thicker plated ferromagnetic film. Processes for manufacturing these shields are also described.

The present invention relates to perpendicular magnetic recording media with improved signal-to-medium noise ratio (“SMNR”) and thermal stability, which media include a pair of vertically spaced-apart perpendicular ferromagnetic layers which are anti-ferromagnetically coupled (“AFC”) across a non-magnetic spacer layer. The invention is of particular utility in the fabrication of data/information storage and retrieval media, e.g., hard disks, having ultra-high areal recording/storage densities.

A magnetic memory is composed of: a magnetoresistance element including a free magnetic layer; a first interconnection extending in a first direction obliquely to an easy axis of the free magnetic layer; a second interconnection extending in a second direction substantially orthogonal to the first direction; and a write circuit writing data into the free magnetic layer through developing a first write current on the first interconnection, and then developing a second write current on the second interconnection with the first write current turned on. The free magnetic layer includes: first to N-th ferromagnetic layers and first to (N−1)-th non-magnetic layers with N being equal to or more than 4, the i-th non-magnetic layer being disposed between the i-th and (i+1)-th ferromagnetic layers with i being any of natural numbers equal to or less than N−1. The free magnetic layer is designed so that antiferromagnetic coupling(s) between the j-th and (j+1)-th ferromagnetic layers is stronger than that between the first and second ferromagnetic layers, j being any of integers ranging from 2 to N−2.

A magnetoresistive memory cell includes a magnetic tunnel junction (MTJ). The MTJ includes a magnetic layer having a pinned magnetic moment, a tunneling layer, and a free layer. The free layer includes first and second ferromagnetic layers having respective first and second free magnetic moments, which are anti-ferromagnetically coupled to each other and align with a preferred axis of alignment in the absence of an applied magnetic field. The MTJ has an electrical resistance dependent on the direction of one of the free magnetic moments. The memory cell also includes a guide layer formed of a ferromagnetic material providing a guiding magnetic moment, which is configured and positioned so that the guiding magnetic moment is more strongly magnetically coupled to the second free magnetic moment than to the first free magnetic moment, and is aligned with the axis in the absence of the applied magnetic field.

A method and system for providing a magnetic junction usable in a magnetic memory are described. The magnetic junction includes first and second pinned layers, first and second nonmagnetic spacer layers, and a free layer. The first pinned layer has a first pinned layer magnetic moment and is nonmagnetic layer-free. The first nonmagnetic spacer layer resides between the first pinned and free layers. The free layer resides between the first and second nonmagnetic spacer layers. The second pinned layer has a second pinned layer magnetic moment and is nonmagnetic layer-free. The second nonmagnetic spacer layer resides between the free and second pinned layers. The first and second pinned layer magnetic moments are antiferromagnetically coupled and self-pinned. The magnetic junction is configured to allow the free layer to be switched between stable magnetic states when a write current is passed through the magnetic junction.

A method to switch a scalable magnetoresistive memory cell including the steps of providing a magnetoresistive memory device (12) having two bits (18) and (20) sandwiched between a word line (14) and a digit line (16) so that current waveforms (104) and (106) can be applied to the word and digit lines at various times to cause a magnetic field flux H_W and H_D to rotate the effective magnetic moment vectors (86) and (94) of the device (12) by approximately 180°. Each bit includes N ferromagnetic layers (32) and (34, 42) and (44, 60) and (62, 72 and 74) that are anti-ferromagnetically coupled. N can be adjusted to change the magnetic switching volume of the bit. One or both bits may be programmed by adjusting the current in the word and/or digit lines.

A spin injection magnetic domain wall displacement device has a plurality of spin injection magnetic domain wall displacement elements. Each element includes a magnetic domain wall displacement layer having a magnetic domain wall, and a first, second, and third magnetic layer groups each having a ferromagnetic layer. The first, second, and third magnetic layer groups are disposed in the order on the same side of the magnetic domain wall displacement layer. The magnetic domain wall is displaceable by flowing electrons between the first and third magnetic layer groups. The position of the magnetic domain wall in the magnetic domain wall displacement layer is detectable based on the difference in the electrical resistance across the second and first or third magnetic layer groups. The magnetic domain wall displacement layer is in antiferromagnetic coupling with the first magnetic layer group, and in antiferromagnetic or ferromagnetic coupling with the third magnetic layer group. The element enables detection of displacement of the magnetic domain wall by measuring the change in the electric resistance.

A perpendicular write head includes a main pole comprising high moment magnetic layers laminated with both soft magnetic layers and non-magnetic layers for antiferromagnetic coupling (AFC) between the high moment material layers.

Embodiments of the invention provide a perpendicular magnetic recording medium improved for fly ability, high in read signal quality, and capable of suppressing magnetic decay of recorded magnetization to be caused by stray fields. In one embodiment, a perpendicular recording layer is formed over a substrate with a soft magnetic underlayer therebetween, then an amorphous or nano-crystalline layer is formed between the substrate and the soft magnetic underlayer. The soft magnetic underlayer includes first and second amorphous soft magnetic layers, as well as a nomnagnetic layer formed between those first and second amorphous soft magnetic layers. The first and second amorphous soft magnetic layers are given uniaxial anisotropy in the radial direction of the substrate respectively and coupled with each other antiferromagnetically.

A current sensor including a magnetic detecting bridge circuit which is constituted of four magneto-resistance effect elements with a resistance value varied by application of an induced magnetic field from a current to be measured, and which has an output between two magneto-resistance effect elements. The four magneto-resistance effect elements have the same resistance change rate, and include a self-pinned type ferromagnetic fixed layer which is formed by anti-ferromagnetically coupling a first ferromagnetic film and a second ferromagnetic film via an antiparallel coupling film therebetween, a nonmagnetic intermediate layer, and a soft magnetic free layer. Magnetization directions of the ferromagnetic fixed layers of the two magneto-resistance effect elements providing the output are different from each other by 180°. The magnetic detecting bridge circuit has wiring symmetrical to a power supply point.