Planar Magnetic Domain Wall Memory Using Constricted Write Wires
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Solution Overview
Problem
Conventional magnetic bubble memory technologies face limitations in speed, track density, and physical defects, making them impractical for high-density, non-volatile memory applications, while existing domain wall memory concepts are complex and costly to fabricate.
Innovation Solution
A high-density, planar magnetic domain wall memory apparatus with coplanar shift register structures formed from ferromagnetic material, featuring discontinuities for domain wall location, and using magnetic read and write elements with constricted write wires for efficient data shifting and storage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If conventional magnetic bubble memory is used, then non-volatile storage is achieved, but speed and track density are limited
Solution Approach 1:
The patent changes the fundamental parameters of magnetic memory by transitioning from macroscopic bubble domains to microscopic domain walls in nanoscale wires. This involves changing the scale (from micrometer to nanometer), the magnetic structure (from isolated bubbles to continuous domain walls), and the control mechanism (from external fields to spin-polarized current), thereby achieving both high speed and high density while maintaining non-volatility
Solution Approach 2:
The patent moves from two-dimensional bubble memory to three-dimensional domain wall structures in nanowires, utilizing vertical stacking of multiple memory layers. This dimensional transition enables higher track density and allows independent addressing of multiple bit planes, significantly increasing storage capacity without sacrificing access speed
2Productivity
If domain wall memory concepts are implemented, then high density and speed are achieved, but fabrication complexity and cost increase
Solution Approach 1:
The patent segments the magnetic memory structure into modular nanowire units with discrete domain walls, where each wire can be independently fabricated and addressed. This segmentation allows standard semiconductor fabrication techniques to be applied to each module, reducing overall fabrication complexity while enabling high-density parallel processing and stacking
Solution Approach 2:
The patent designs a universal nanowire domain wall structure that can be fabricated using existing semiconductor processes, making the same basic structure applicable across different memory densities and configurations. The domain wall memory element serves multiple functions: storage, shifting, and reading, reducing the need for separate specialized components
3Speed
If external magnetic fields are used for shifting bubbles, then macroscopic bubble memory operates, but speed decreases and power consumption increases
Solution Approach 1:
The patent replaces the mechanical/external magnetic field system with a spintronic system where spin-polarized electrons directly exert force on domain walls through the spin transfer torque mechanism. This substitution eliminates the need for large external magnetic fields, enabling localized, fast, and energy-efficient domain wall manipulation at the nanoscale
Solution Approach 2:
The patent introduces spin-polarized current as an intermediary between the electrical control signal and the magnetic domain wall. The spin-polarized electrons serve as the mediator that transfers angular momentum to the domain wall, enabling precise, localized control without requiring direct magnetic field application, thereby reducing power consumption and increasing speed
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution enables fast, reliable, and high-density data storage with error correction capabilities, reducing production costs and complexity by using existing semiconductor processing techniques and minimizing silicon transistor usage.
Implementation Method 1
By flowing a sufficiently large spin-polarized current along the nanowire, enough force is imparted from the electrons onto the domain walls such that the domain walls may be moved along the wire
Implementation Method 2
Through judicious application of magnetic fields to this fixed tape, the bubbles are made to move or shift along the tape as in a shift register
Data Source
AI summary
A magnetic domain wall memory apparatus with write/read capability includes a plurality of coplanar shift register structures each comprising an elongated track formed from a ferromagnetic material having a plurality of magnetic domains therein, the shift register structures further having a plurality of discontinuities therein to facilitate domain wall location; a magnetic read element associated with each of the shift register structures; and a magnetic write element associated with each of the shift register structures, the magnetic write element further comprising a write wire having a constriction therein, the constriction located at a point corresponding to the location of the plurality of discontinuities in the associated shift register structure.