摘要:
A method for forming a memory device includes forming a cavity having an inner surface with an undulating profile in a substrate, depositing a ferromagnetic material in the cavity, forming a reading element on the substrate proximate to a portion of the ferromagnetic material, and forming a writing element on the substrate proximate to a second portion of the ferromagnetic material.
摘要:
A method for forming a memory device includes forming a cavity having an inner surface with an undulating profile in a substrate, depositing a ferromagnetic material in the cavity, forming a reading element on the substrate proximate to a portion of the ferromagnetic material, and forming a writing element on the substrate proximate to a second portion of the ferromagnetic material.
摘要:
An active memory element is provided. A bipolar memory two-terminal element includes polarity-dependent switching. A probability of switching of the bi-polar memory element between a first state and a second state decays exponentially based on time delay and a difference between received signals at the two terminals and a switching threshold magnitude.
摘要:
A magnetic data track used in a magnetic shift register memory system may be fabricated by forming a multilayered stack of alternating dielectric and/or silicon layers. Vias of approximately 10 microns tall with a cross-section on the order of 100 nm×100 nm are etched in this multilayered stack of alternating layers. Vias may be etched form smooth or notched walls. Vias are filled by electroplating layers of alternating types of ferromagnetic or ferrimagnetic metals. The alternating ferromagnetic or ferrimagnetic layers are comprised of magnetic materials with different magnetization or magnetic exchange or magnetic anisotropies. These different magnetic characteristics allow the pinning of magnetic domain walls at the boundaries between these layers. Alternatively, vias are filled with a homogeneous ferromagnetic material. Magnetic domain walls are formed by the discontinuity in the ferromagnetic or ferromagnetic material that occurs at the notches or at the protuberances along the via walls.
摘要:
A magnetic shift register uses the inherent, natural properties of domain walls in magnetic materials to store data. The shift register uses spin electronics without changing the physical nature of its constituent materials. The shift register comprises a fine track or strip of magnetic materials. Information is stored as domain walls in the track. An electric current is applied to the track to move the magnetic moments along the track past a reading or writing device. In a magnetic material with domain walls, a current passed across the domain wall moves the domain wall in the direction of the current flow. As the current passes through a domain, it becomes “spin polarized”. When this spin polarized current passes through the next domain and across a domain wall, it develops a circle of spin torque. This spin torque moves the domain wall.
摘要:
A magnetic recording data storage system uses a medium substrate with multiple data layers formed on it and a magnetoresistive (MR) read sensor that provides a direct digital output as it reads data in all the data layers simultaneously. In one disk drive embodiment, the magnetic recording disk is a conventional disk substrate with two magnetically isolated and decoupled magnetic data layers formed on it. Data is written into each of the data layers independently by appropriate selection of the coercivity of the magnetic materials used in the data layers and the strength of the write current in an inductive write head. In one embodiment for independently writing to any of the data layers, the data layers are made of magnetic materials having different coercivity vs. temperature dependencies, and the disk is heated (or not heated) prior to writing with a write field that affects only one of the data layers. The magnetic field strength from written data in each of the data layers is different from that of the other data layers so that the data can be distinguished by the MR read sensor. The preferred MR read sensor for the multiple data layer disk is a multilayer of alternating ferromagnetic layers and nonferromagnetic metal spacer layers based on the giant magnetoresistive (GMR) effect. However, in the present GMR sensor each ferromagnetic layer has its magnetic moment responsive to an external magnetic field strength that is different from the magnetic field strengths at which the magnetic moments of the other ferromagnetic layers are responsive. This allows each ferromagnetic layer in the GMR sensor to switch its magnetization direction from parallel to antiparallel, or vice versa, independently of the other ferromagnetic layers.
摘要:
A spin valve magnetoresistive (MR) sensor uses a multifilm laminated pinned ferromagnetic layer in place of the conventional single-layer pinned layer. The laminated pinned layer has at least two ferromagnetic films separated by an antiferromagnetically coupling film. By appropriate selection of the thickness of the antiferromagnetically coupling film, depending on the material combination selected for the ferromagnetic and antiferromagnetically coupling films, the ferromagnetic films become antiferromagnetically coupled. In the preferred embodiment, the pinned layer is formed of two films of nickel-iron (Ni--Fe) separated by a ruthenium (Ru) film having a thickness less than approximately 10 .ANG.. Since the pinned ferromagnetic films have their magnetic moments aligned antiparallel with one another, the two moments can be made to essentially cancel one another by making the two ferromagnetic films of substantially the same thickness. As a result, there is essentially no dipole field to adversely affect the free ferromagnetic layer, which improves the sensitivity of the sensor and allows higher recording density to be achieved in a magnetic recording data storage system.
摘要:
A magnetoresistive (MR) sensor comprising a first and a second thin film layer of a magnetic material separated by a thin film layer of a non-magnetic metallic material. The first ferromagnetic layer is magnetically soft. The magnetization direction of the first layer of magnetic material is set substantially perpendicular to the magnetization of the second layer of magnetic material at zero applied field, and the magnetization direction of the second layer of magnetic material is fixed. A current flow is produced through the MR sensor, and the variations in voltage across the MR sensor are sensed due to changes in resistance of the MR sensor produced by rotation of the magnetization in the first layer of magnetic material as a function of the magnetic field being sensed. The variation of the resistance with the angle between the magnetizations of the first and second layers of magnetic material has been defined as the spin valve (SV) effect. It is also shown that, by a suitable direction of the current with respect to the fixed magnetization, the (SV) magnetoresistance can be added constructively to the usual anisotropic magnetoresistance.
摘要:
A magnetoresistive (MR) sensor comprising a layered structure formed on a substrate includes a first and a second thin film layer of magnetic material separated by a thin film layer of non-magnetic metallic material such as Cu, Au, or Ag, with at least one of the layers of ferromagnetic material formed of either cobalt or a cobalt alloy. The magnetization direction of the first ferromagnetic layer, at zero applied field, is set substantially perpendicular to the magnetization direction of the second ferromagnetic layer which is fixed in position. A current flow is produced through the sensor, and the variations in voltage across the MR sensor are sensed due to the changes in resistance produced by rotation of the magnetization in the front layer of ferromagnetic material as a function of the magnetic field being sensed.
摘要:
Stable, bulk electrical superconductors are prepared by heating mixed metal oxides in the presence of oxygen in a closed vessel in a preheated oven for 1-5 hours at 850.degree.-900.degree. C. The final oxides are in the molar ratio Ti.sub.0.6-1.1 Ca.sub.2-3 Ba.sub.0.75-1.25 Cu.sub.2-3 O.sub.(5+.delta.)-(9+.delta.), where .delta. is less than one.